Dropbox is 8/10 on their BS index. Dropbox may not produce enlightenment, but it sure solves a useful problem of storing and sharing files online. I think they're doing well financially too?

I seem to remember reading a Paul Graham article about the early days of Y Combinator (can't find the article now) where he mentioned that basically 2-3 startups including dropbox make all the money, and the rest is just noise. Seems like it wasn't such a BS bet after all.