Just three years ago, a pair of MIT grad students introduced a nifty little computer program called VisiCalc. Designed for the Apple personal computer, VisiCalc was modeled after the standard accountants' spreadsheet: a table of rows and columns with numerical entries.

However, VisiCalc was like a spreadsheet on magic paper--whole row and column entries could be changed at the peck of a few computer keys. Accountants and managers could explore a variety of "what if?" options without lifting a pencil or touching a calculator. Building financial models became a snap.

"There were actually accountants who liked their work because of VisiCalc," says Dan Bricklin, the program's co-creator and chairman of Software Arts, a software development company in Cambridge, Mass., that markets it.

VisiCalc slowly caught on. Positive word-of-mouth boosted sales. Some people were so impressed by what the program could do that they actually went out and bought computers to enable them to use it.

Today, Bricklin estimates, over 300,000 copies of VisiCalc have been sold. Reportedly, even the accountants at the Office of Management and Budget use it. VisiCalc has become such a monster software hit that it's practically become an industry cliche.

But the industry VisiCalc grew up in has changed. Where VisiCalc practically had to sell itself, today, says Bricklin, "We just hired a new marketing person."