Ya gotta be careful with those cloud-based accounts.. especially free ones... a lot of them (google and ms come to mind) have a nice little addition to their terms that basically means anything you post on their servers becomes their commercial property. I don't think they flex that muscle often, but it's something i've seen and since thought twice about hosting important things.
Dropbox may be different, I don't use it so I don't know... also it usually changes if you pay for the space.
I have my own webspace that's got unlimited space that I got for $4/month... It's got full SSH/FTP/MAIL features so I use that... I'm not supposed to use it for storage, but unless i abuse it i'm sure it's not a big deal.