Everybody's got junk and often not enough room to stow it. When Public Storage is a little out of your price range, there's Store At My House, a new service that matches people who need to store stuff with those who have space for it. You can register to rent out your attic, an extra room, or even a parking space. Entries are displayed on a Google map, and you can sort through listings on a sidebar for whatever type of space is needed. If it's not there, there's a request form for others browse and message you if they have something that matches your needs.
There are some interesting liability issues with this idea, particularly how to sort the trustworthy individuals from the potential crooks. There's also the limitation of having to rely on someone else's timetable and availability in order to access your goods. There is a sample contract provided by the service to help you figure these things out ahead of time, but not nearly the kind of peace of mind you'd get with a local storage unit.
We've seen some other sites play around with the idea of loaned storage. CrashPlan lets you stash your data, although you don't have to pay for it beyond a license for the program and having some friends with extra space on their hard drives. In the case of Store At My House, the idea of having personal items compromised or stolen will likely be too unnerving for casual users.