[unalone]

But Wufoo still deals with a Big Idea: namely, something that's creating a large infrastructure on the Internet. 37signals is a private, internal service: they make things that appeal to closed niches. On the other hand, Wufoo is something that's more public, in a sense.

Maybe it's just a matter of what YC companies get named more than others, but the ones that immediately come to mind are big-problem companies. Reddit for finding news online. Disqus for comments. Scribd for document indexing. Wufoo for forms. There aren't as many niche sites (versus something like TechStars, which had a cooking site) - or am I just missing lots of niche YC sites?

[pclark]

even the smallest niche can be huge.

[unalone]

Absolutely. Furthermore, niche users tend to be more fanatic about the sites they use if they're done well.