I'm not sure what you mean about 'all this funding for file sharing sites', but I haven't been following the sector closely.<p>What you will often find is a gang mentality within sectors. Investors won't get in on one-deal, but they may think the sector is going to experience huge growth, so they invest in the next best company. We saw it with Foursquare, gowalla, etc.etc, as well as groupon, livingsocial...<p>It seems the distribution is normally a big dog, an also ran, and then everybody else fighting for scraps.<p>With respect to why Dropbox is interesting, it is my understanding that the interesting parts aren't that you as a user can store and share your files. I think the long-term potential is for applications you interact with to access your data through services like dropbox. This could mean that you don't end up paying for it directly, but rather it would be built into the costs of other services you use.<p>Think of it like iCloud, but for all platforms and open to any developer. That's my understanding of where Dropbox is going, but like I said, I don't follow that segment.