Zooomr is allowing current users to invite new users, and those new users automatically get a free pro account!!
So if you want in, drop me a comment :D
** UPDATE **
OK after re-reading KT’s message a bit more it would appear that the person doing the inviting gets +PRO, not the invitee (invited person). So sign up and invite someone else to get your pro account!
photos, photosharing, zooomr
I think the inviter gets free pro account - not the invitee. Am I wrong?
Hmm good point, I guess I don’t really know the answer. I just assumed it made more sense to give it to the invitee - certainly in the sense that you invite two people and they both sign up it does, but the invite page is unclear :(