I like Dropbox but I also use Cubby as well.

Cubby is a competitor to Dropbox whose main selling points are that Cubby will synchronize any set of parent folders located anywhere (not only one specific one) and that files are stored on their servers with a higher level of encryption. Local side encryption is also available.

Another feature is that you can have Cubby directly sync files between computers (and not stored on their servers at all).

Ron