When AppNet Inc. of Bethesda went public in June, investors yawned, then walked away.

The World Wide Web site creator's stock never budged above its offering price of $12 a share on the first day of trading and then drifted down to $8.81 1/4 the following week.

AppNet stock crawled back to about $15 a share soon after and languished there until early last month, when a Credit Suisse First Boston analyst decreed that building Internet storefronts for companies getting into electronic commerce was a great business. "The stock is way too cheap," he said. "It has a 200 percent upside."

Credit Suisse First Boston happens to be the investment firm that took AppNet public, but the obvious self-interest didn't deter investors, who in one day ran the stock up to $33 a share from $15.50.

Last Friday AppNet's stock jumped $13.68 3/4 a share to an all-time high of $56.68 3/4, making the company one of the local leaders of the latest trend in technology stocks.

It's not companies with exotic ideas for doing business over the Internet that investors are buying now, it's companies that can make those ideas work.

The four fastest-flying initial public offerings so far this year in the Washington region are companies with names that probably never will become household words. It's their customers who are bound for Internet glory, but AppNet, Proxicom Inc., Cysive Inc. and Aether Systems Inc. are building their stairways to heaven.

AppNet, the stock of which is up 372 percent since its IPO, is on the conceptual and creative end of electronic commerce, developing business strategies, marketing campaigns and merchandising systems for companies that take their act onto the Net.

Proxicom and Cysive are the back-room boys of the Internet business. The companies, based in Reston, build the software that goes to work when someone clicks a button to buy something from an Internet merchant, book a hotel room online or bank electronically.

Proxicom stock gained almost $20 last week, closing Friday at a record $79 a share, up 508 percent since its IPO April 20. Though Proxicom's founder, Raul Fernandez, was a high-profile player in the Washington Internet world, the stock made only a respectable 43 percent jump -- to $18.68 3/4 from $13 -- on its first day of trading.

But investors had discovered electronic commerce software companies by the time Cysive hit the market a week ago. Its shares jumped from the offering price of $17 a share to $37.75 on the first day of trading Oct. 15. After another big jump Friday the stock closed at $47 a share, up 176 percent in its first six days in the market.

Though Cysive founder Nelson A. Carbonell Jr. lists Proxicom as his most direct local competitor, the market regards Proxicom not as a dangerous rival but a delightful roadmap of where Cysive's stock could go.

Based in Owings Mills, Md., Aether is more a telecommunications company than an Internet play, but the Net is an integral part of its business -- not just the publicly accessible Internet but the private intranets and extranets used by corporations for internal and external communication.

Like Cysive and Proxicom, Aether aims to become essential to the success of a new generation of technology -- hand-held wireless communications devices that make it possible for people on the move to do the same tasks they accomplish at a desktop computer.

Dozens of companies are working on ventures that make use of cellular phones or pocket pagers souped up with small video screens, personal organizers such as the Palm Pilot and mini-laptop computers as communications devices that link up with the Internet or corporate computer systems.

Trouble is, there are all kinds of pocket devices that use lots of different internal operating software. The devices communicate over cellular, satellite, paging and special-purpose wireless networks. And they need to link up with host computers using an even bigger assortment of hardware and software.

Aether founder David Oros came up with technology to make all those things speak the same language, an interface that is agnostic as to software, hardware and communications network.

Instead of selling the software, Aether is set up as a service, a central facility with a turnstile that will collect a token fee from every customer who routes traffic through its system. The buzzword for investors is "recurring revenue stream."

The first big-name user is Morgan Stanley Dean Witter's Discover brokerage, which uses Aether's system to let clients trade stocks online from their cell phones, Palm Pilots or pagers. Charles Schwab and other brokers are signed up to offer similar services. Aether recently bought a company that offers wireless currency, bond and futures trading; Reuters Group PLC, another big investor, is sending its financial news via the system.

Electronic mail and Internet access are essential features of Aether's system, but the big target is connecting corporate America to mobile workers, replacing telephone modems with wireless devices such as the Palm Pilot. Another big investor in Aether is 3Com Corp., which makes the Palm pilots, but the company is committed to communicating with all competing machines as well.

The closest thing to a direct competitor is Phone.com, a California company that makes the system used on the Internet phones sold by Sprint. Since Phone.com went public June 11 at $16, its stock has blasted to $229.25 as of the close of trading Friday.

Just as investors looked at the performance of Proxicom stock and speculated that the same thing could happen to Cysive, they're betting that Aether could follow Phone.com.

Aether's IPO began trading last Thursday and tripled on the first day, up from $16 a share to $48.81 1/4. Not surprisingly, the stock pulled back Friday, closing down $4.43 1/4 at $44.

Though Aether plays a similar role as Cysive, Proxicom and AppNet, it is a much younger company. Unlike the many start-ups that emphasize generating revenue without regard to profit, Cysive, Proxicom and AppNet make money.

Aether founder Oros's comment that "this is not a revenue story" is a considerable understatement. Aether's revenue in the first half of this year was a mere $787,000 and only $598,000 of that came from the few thousand customers of the data and trading services it runs for Reuters, Morgan Stanley Dean Witter and other clients.

A resonably good restaurant or a decent dress shop would serve as many customers in six months and could easily ring up more sales than Aether. Yet Aether is valued by Wall Street at more than $1.1 billion, based on the total value of all its outstanding stock as of the close of Friday's trading. Cysive's market capitalization stands at $523 million, AppNet's $1.76 billion and Proxicom's rounds off to $2 billion.

Those may sound like Internet valuations from the olden days -- circa 1998.

But this year's hot tech companies are different from Amazon.com and so many Internet merchants and services. Those companies with inflated -- or formerly inflated -- stock prices operate under business plans that call for generating as much revenue as possible without regard to profits. Their mission is to build a base of customers, then concentrate on making money.

No one on the Net, certainly not Amazon.com Inc., has demonstrated that the "if you build it, profits will come" model actually works. Doubts about that concept are one factor behind the depressed stocks of so many Net companies in the region. Shares of Value America Inc., MusicMaker.Com, CareerBuilder Inc., Online Resources & Communications Corp., OneMain.Com and CAIS Internet Inc. are all down sharply from their offering prices.

Those companies from the previous generation of hot tech stocks have burned a lot of investors. They're still eager to bet on the Net, but they're a lot more comfortable putting their money into companies that have proven they can do something, such as Proxicom, AppNet, Cysive and Aether.

Maybe Internet investors are finally wising up.