A question from Yahoo! Answers:
What business can I start from scratch thatll become as big as microsoft IN MY LIFETIME??
The reason Microsoft got big was a mistake made by IBM, which decided to outsource the development of DOS instead of developing it in-house. Without the DOS franchise (which eventually became the Windows franchise) handed to it by IBM on a silver platter, Microsoft would be just another Borland or WordPerfect.
So the answer to your question is rather obvious; you can start any business, provided that a Fortune 500 company puts you into a dominant position not only over itself, but over the entire industry it is trying to create at the moment. But how likely to happen is that?