gDisk - very cheap (free) online storage
I’ve used this for a while but haven’t got round to mentioning it.
Basically, it uses a gmail account (curently offering around 2.7GB space) as online storage, accessed seamlessly from this app. Mac Os X only I’m afraid although I’m sure I’ve heard of Windows alternatives.
I’m not sure if gmail is still invite only, but if it is, and if someone reading doesn’t have a gmail account, let me know as I have plenty of invites.