The best thing to do is buy a USB blutooth dongle. You can find them on ebay for �15 or so.. They can be used to send games, themes, photos, contacts, etc back and forth between your PC and phone. If you want to send a lot of stuff you'll save money in the long run by doing that seeing as MMS or email would cost 25p + every time you send a photo.
Unfortunately I don't know of any sites that let you upload photos to them via your phone and download them on your PC. I got a dongle =)