I just put up a bunch of free app codes over at codehookup.com. It’s a really interesting site in that you can target social users instead of standard reviewers, the way you would using Tokens. I love Tokens, but it really isn’t meant for broadcast sharing.
You paste your iTunes link. The site pulls out your app info and creates a button. You click that go to the share page, shown here. Paste in your codes, and click Share.
Make sure you make a note of the link it provides you, because that URL is the only way you have to provide those code to the public.