Hangers are a good ukulele storage alternative to ukulele stands if floor space is at a premium or you have a really big collection. Another reason that you might prefer hangers to stands is that they are often more decorative. Tiki themed hangers seem to be very popular.
If at all possible, get a hanger that's made for the ukulele. A mandolin or banjo hanger would probably work, but if I'm suspending my ukuleles a few feet in the air I don't want to be taking too many risks.