I was browsing Amazon for a game or two and I noticed that they have started a new download section.

Looks pretty cool and will come in handy I'm sure.

http://www.amazon.co.uk/b?ie=UTF8&node=2683271031

I had a look over on Amazon.com and I think they do do downloads as well but it's working in another way, when you look for a game and it gives you the option PS3, Xbox etc. there is also a download version for the PC, I noticed it's not on all games.