Last week, we looked at the geeks who created iconic technologies. This week, we examine the executives who pushed those technologies into becoming the basis of some of the largest businesses in the world.

The chief executive is the rock star; they are the face of the company and the ones ultimately saddled with billion-dollar decisions that can make or break entire markets, and leave their staff either much richer or asking if you want fries with that.

So what makes a good chief executive? Leadership, both internally and to the world outside is important. So too are brains, but not as much as you'd think. After all, leaders have geeks for that. Business sense is critical, but so too is knowing when to throw out the prevailing wisdom and follow your instincts.

One thing not needed is a charming personality. Many of the people on this list, particularly the top three, sometimes show the personal skills of a grumpy Attila the Hun and possess all the charm of a serious road accident. But maybe that too is needed in the corporate world; as legendary baseball manager Leo Durocher put it: "Nice guys finish last."

As ever this was a tough list to compile, not just in whittling the possible candidates down but especially in their position on the grid, and we've included a couple of 'honourable mentions' at the very end.

There's a lot of good talent in the software industry (and some absolute idiots, as next week's list will show) and that's a sign of how mainstream the technology has become.