A couple of years ago I proposed an idea for "AirBnB for self storage" on Quora: http://www.quora.com/Collaborative-Consumption/What-is-the-n...
Still seems like a massive opportunity. $24 billion market in the US. Inconvenient locations (for many people). People have (collectively) a massive amount of under-utilized space. Not without its challenges but neither was AirBnB when it started.