Twit Invite keeps an eye out for tweets asking for invites to websites that are in an invite-only, beta or alpha phase of testing. The service then responds to the user with a link to more information including any invite codes and signup details.
http://twitter.com/twitinvite
http://twitinvite.com
http://twitter.com/ollieparsley
http://ollieparsley.com
http://twitter.com/twitinvite
http://twitinvite.com
http://twitter.com/ollieparsley
http://ollieparsley.com
