Has anyone used StumbleUpon? And is it really that cool? It looks like eBay may think so -- though we can't really see how a company like StumbleUpon fits into eBay's wheelhouse.

Okay, so eBay bought StubHub, the place where you can sell and buy concert and sports tickets--but that really plays to eBay's strengths, right? Helping people with buying and selling stuff? Perhaps the company imagines using StumbleUpon's tech to help users find better targeted auctions.Or perhaps is it just an attempt to diversify?

Either way, if true, this fits very much with the trend of established companies like eBay buying up-and-comers--similar to MySpace to News Corp., Flickr to Yahoo!, YouTube to Google, etc. In this case, we'd be interested to see the idea behind making money with such an acquisition--an aspect often hard to determine in these "big fish gobbling little fish" situations.