"Stay in touch with the potential cofounders you've already found."

I met my cofounder when we lived across from each other in college at the Arts Theme House. We just didn't know we were cofounders yet. At the time, I was a physics major - my cofounder knew that I had previously worked at a tech startup, but he had no idea that I was still into computers (I'm not sure I was, at the time), or that I'd done several major side projects. I knew him as a psych major who was a bit of an electronics whiz - I had no idea that he wanted to go into entrepreneurship or the Internet space. For that matter, I don't think he did either.

I didn't find out what he was doing until I went over to catch up with him at Homecoming. I knew that he'd been at a consulting firm (via FaceBook), but usually consultants go into big business instead of Web2.0 startups. Even then, I didn't join immediately - he had someone else picked out as a technical cofounder. It was only after the previous technical cofounder quit (for visa reasons) that I joined up with him.

Also - there's a common misconception that top-notch hackers spend all their time hacking. They spend a lot of time hacking, but most have other interests. For example, Guy Steele sings bass in choir and does swing dancing. Paul Graham writes essays and paints. One of the top hackers I knew at college was a CS/Theater double major. IMNSHO, these people often have better technical chops than the single-minded, socially awkward computer geek.