Image Hosting

[The_Hawk]

I'm on the hunt for something a little outside the box (or so it seems).

I'm on the hunt for some image hosting software to complement my vBulletin install, but to be run on a separate server. Integration would be nice, but not essential. The only reason I don't want to have a gallery built into my vBulletin install is bandwidth. My current server is fixed bandwidth but I have others with unlimited bandwidth I'd like to use to host the images. (So if there is an off the shelf integrated vBulletin package which allows inline image upload + storage off site on another server, that would be very interesting too).

So I'm looking for:
Ideally something which is easy to upload images.
Something which auto resizes images, provides links back the full size image and spits out BB Code. Some sort of auto sign up for users which can be switched between auto, manual and off.
The ability for non registered/non logged in users to view galleries would be nice too.

The idea here is that I would like to encourage users to use my hosting so I can provide instructions that will work for everyone. Free access to all users, while I can also control the server they are on so can deal with speed/capacity/latency issues as well as controlling image size a little more (and hopefully ensure images are retained for a longer period).

Any suggestions or recommendations?