And for my next trick

Kai Krause's small but perfectly formed graphics packages are popular because they work the way we do. Is he now about to turn his genius to developing a new interface? By Stephen Pritchard

In a business with more than its share of unconventional visionaries, Kai Krause still manages to be slightly different. It is not just his imposing figure and persona, but his genuine and almost childlike enthusiasm for writing good software.

A combination of simplicity and power has taken Krause's products to the top of the best seller lists. This should be no surprise. Krause says, he numbers his eight-year-old daughter among his alpha testers. It is unlikely that he is joking.

Krause, 39, is originally from Essen, Germany. He came to prominence as an expert in digital imaging - the Adobe Photoshop user par excellence. He moved from providing Photoshop hints and tips on America Online to writing his own add-ons, Kai's Power Tools (known as KPT), for Adobe's flagship product.

KPT brings some of Krause's creative magic to the ordinary Photoshop user. His filters make it far easier to build dreamy, alien landscapes, and designers have gone on to produce Web pages, album covers, even art for its own sake, with the package. In the process, they have made Krause rich, a circumstance which seems to surprise him.

Krause's firm, MetaTools, is worth more than $350m. This is all the more remarkable given that Krause specialises in products that are small, sometimes even single-function, adjuncts to software written by other people.

Krause is a success because his products focus on a limited number of tasks, then do them well. Hot talk in the industry right now is of "middleware": pieces of code that sit between the operating system and program, adding functions. Apple's QuickTime, and possibly Sun's Java, fall into this category. But Krause's products are best described as "littleware" - small, cheap programs that users are happy to buy on price. There are a lot of users out there, and once bought, few delete MetaTools's products from their hard disk.

One reason is the look of MetaTools's software. Krause's programmers lovingly craft unconventional and intuitive interfaces on top of the code. Instead of pull-down menus, there are rounded, almost tactile buttons. The screens are textured and highly detailed, but instantly change their functions to match what the user is doing. Krause's forthcoming product, Soap, designed to tidy up scanned or digital images, paints out scratches in an easy, flowing motion that is so natural it hides the raw power underneath.

Krause's team of programmers is also adept at squeezing the last drop of power out of a computer chip. In an industry where ever-faster chips and ever-fatter software seem locked in a bizarre, never-ending circle, this is a rare attribute.

It is easy to sense that Krause, and probably his team, too, are not satisfied by writing graphics software alone. Krause has hinted that the challenge he is seeking is to develop a computer interface. He has talked with Apple, currently in the process of developing a new operating system, and Intel, which is apparently frustrated with the hardware demands made by Windows.

"I don't want to write an operating system," Krause says. But he believes that where the human meets the machine, there is much scope for improvement. "I can throw my hat in the ring."

Soap is itself a product of MetaTools' Amazon, a powerful development environment. Krause could probably release Amazon now - industry sources say it would be a Photoshop killer - but Krause prefers a piece-by-piece approach. He believes this is the way the industry is heading, with small packets of software, distributed over the Web, and maybe even rented for a day.

But there is also a sneaking suspicion that Krause is teasing us. Some of the Amazon technology will be given away, he says, not least with Soap. One of the most impressive pieces of software that Krause demonstrates is a file-finding utility. Krause rejects the idea that files and folders are outdated and restrictive. Instead, his utility stacks files - images, but they could be documents, too - in piles, much as we arrange paper on our desks in the real world. They can be spread around, shuffled and browsed until the right one is found.

Kai Krause is a firm believer in creative mess, and that computers should reflect the way we live and work, not vice versa. So the prospect of Krause taking on an operating system, or even part of it, is a fascinating one