To get his Internet company off the ground, Michael Chen makes a hundred decisions a week. For the two or three that are crucial, he goes virtual and calls Randy Komisar.

A combined professional mentor, minister without portfolio, in-your-face investor, trouble-shooter and door opener, Komisar provides on-demand leadership for Chen's Ugripe and six other Silicon Valley firms, mostly from the serenity of his garden.

Today, for instance, Chen must decide when Ugripe, which is designed to mediate between angry consumers and clueless corporations, should roll out its Web site. Some of the features won't be ready until October--an eternity, in Internet time. Should the entire site be delayed to wait for them?

No, advises Komisar. "Let it go quickly, get some experience in the market," he says. "When we revise it, we can turn on the PR engine, start to get some attention."

Komisar is an accomplished high-tech hand with 15 years of business experience, something that's in short supply here. At the moment, headhunters say, at least 300 tech companies are looking for seasoned chief executive officers who can take them to the next level.

Given the great demand, an outfit as tiny as the five-person, four-month-old Ugripe has no prayer of attracting an experienced CEO. But Chen and his team know that if they don't get expert assistance, Ugripe may not survive.

"Setting up shop in Silicon Valley is like going into a jungle," says Chen. "You need a safari guide to protect you from the wild animals lurking about."

Enter the virtual executive. "This is a new role at new companies in a new world," says Komisar, who gets a healthy amount of stock in exchange for his advice. "They know they can rely on me as challenges arise. They haven't seen them before, but I probably have."

The 45-year-old Komisar operates independently. Elsewhere in Silicon Valley, the role of the part-time executive is being institutionalized.

The Brenner Group, a management firm, has placed about 50 chief executive officers or chief financial officers in area tech firms. Some work at only one or two companies, while others juggle a half-dozen or even more. All the posts are designed to be temporary, for lengths of up to 18 months.

It's a job that particularly appeals to those who have found they like the thrill of a start-up but weren't keen on the grueling pace, founder Rich Brenner says.

One Brenner executive, Dick Murdock, is now working as a finance officer at seven high-tech firms but says he still has more free time than when he used to work at one. The smallest of his companies has two employees; the largest, 30.

"They typically come to us when they have an urgent need--for a business plan, a financial model, accounting system, a lease line. They've gotten to the point where they recognize a need for experienced financial administrative help, but they don't need it five days a week."

Murdock, 52, has given up trying to explain to friends what he does. He's more than a consultant. He's not a full-time employee at any of his companies--the most he works at any of them is one day a week. But he makes decisions as if he were.

"It's murky," he says. "This is a new model, partly because it's hard to find good people in Silicon Valley, partly because more and more start-ups are comfortable outsourcing a greater number of functions--accounting, legal, human resources."

The more companies Murdock works at, the greater the odds that one of them will hit it big. Of course, since he's only part time, he won't profit nearly as much as the full-timers.

"No question, I'd be a lot better off financially working at just one--as long as it's the right one," says Murdock. "But how good is your ability to predict the next Yahoo? And if you're wrong, the downside is high."

Pushing the virtual envelope even further, the executive search firm David Powell Inc. has just formed a new offshoot to put executives into companies that are barely hatched--where, for instance, they not only don't have a product but also are unsure of exactly what form the product will take.

"We'll take a company from its earliest stages, where it's figuring out what the market is that it's going to develop, to where there's enough meat on the bone to attract a full-time, world-class CEO," says Ken Coleman, president of iCEO.

In less fevered days, the model for forming a new tech company was different: An entrepreneur with a good idea and viable technology would go to a venture capitalist, who would take equity in return for cash to get the business going. The venture capitalist would also help the entrepreneur find the other key members of the team, and sometimes even run the company for a while.

"The venture funds can't do this anymore," says Coleman. "The funds have gotten too big. They need to spend all their time investing. They're pumping all this money at inexperienced teams as fast as they can."

Coleman says he's received calls like this from new entrepreneurs: "I have venture money, but I know I can't do this, I need experienced help." ICEO--an abbreviation of "Interim CEO"--is in the process of placing its first four executives, who will work at either one or two companies for two to five days a week.

To some, bringing in anyone from the outside on a part-time basis, particularly if he's given a chief executive label, is a sure sign that the boom is out of control. A start-up that doesn't have a strong management with a strong vision from the beginning, they argue, doesn't deserve to survive.

Even for those firms where the founders are ready to step aside for more professional management, a temporary CEO is considered a last resort.

The Silicon Valley start-ups that are widely viewed as having done the best job of bringing in new CEOs were the auction site eBay and the search engine Yahoo. While neither Meg Whitman, who worked at the toymaker Hasbro and the florist FTD before arriving at eBay, nor Tim Koogle, who spent much of his career at Motorola before joining Yahoo, were steeped in Valley culture, they were hands-on, full-time, dedicated hires. Both companies have prospered mightily since.

"No one within a company wants to work for a part-time manager," says Bob Bozeman, a general partner with Angel Investors, which funds start-ups. For one thing, all the other employees are betting their careers on this; why should they listen to someone who's not?

Furthermore, Bozeman says, "a start-up is a very intense effort. It's not good to have a part-time shared guy. I worry about accountability. This guy has to hire a staff. Is he going to go for people who blend and create the inner soul of this company? Or for more professional managers?"

Yet, as Bozeman concedes, "Everybody wants someone who's been there before." Consequently, Angel has a program where its companies work with what it calls "mentor capitalists"--on-call experts who are paid a mixture of compensation and stock.

No matter what label is used for the outside authority, Randy Komisar notes, the process will only work if he enhances but doesn't try to replace the in-house executives. "If it were my job to build and operate the business, I would be the full-time CEO, not a virtual one. It's my job instead to guide, direct and help strategize a business around some brilliant person's invention."

Komisar was co-founder of Claris, the software maker for Apple; chief financial officer for the ill-fated, pen-based computing firm Go Corp.; and chief executive of an interactive-game company owned by filmmaker George Lucas.

In 1995, he was asked by WebTV founder Steve Perlman to become CEO of the company, which allows consumers to access the Internet through their television. Komisar turned down the position, but became Perlman's confidant and adviser. The virtual CEO was born. In 1997, Microsoft Corp. bought WebTV for $425 million.

Of Komisar's current crop of companies, the best-known is TiVo, which has developed a system to produce instant replays of live TV and has filed to go public. While the rest are still struggling to make their way, Komisar says none of his companies has ever failed.

"It's still early, though," he adds cheerily. "I guarantee you I will have a failure. I'll have to. We're not here to bat 1.000, just to make sure each idea gets a fair hearing."

When high-tech companies falter, it's often because someone else has exploited their market niche first. That's why the Internet mantra for start-ups is "Go as fast as you can, and then go faster." But Komisar's advice is more sophisticated than that.

"The road to riches in Silicon Valley is being simplified as 'Get in the car and put your foot to the floor,' " he explains. "It's true, a lot of companies have succeeded with that model. But start-ups don't just have accelerators, they have brakes and steering wheels."

He is trying to step on the brakes right now in a conference call with executives at IQ, a developer of online sales promotions that is searching for a better strategy. "You want a decision now," he tells the worried IQ executives. "I want the right decision and to make it soon. But I don't want to just cast about."

In the old days, a new company would have informal mentors and advisers that would help out of sheer benevolence. That model is too creaky, positively 19th century.

"Now speed and accessibility are everything," says Ugripe's Chen, a 29-year-old graduate of Harvard Business School and former consultant. "I could be here with my team, stuck on a key execution or strategy problem, and I can pick up the phone and call Randy. He's available 24-7. Without him, things might be happening more slowly."