According to that site, the games are:
Fish & Reefs (Steam)
Alien Hallway (Steam)
I hope that's not a final list, because I don't think they'll sell many with only two Steam games.
Tomorrow is BIAB, 5/24 is Because We May, and 5/25 is IFK. Including today's Groupees, we get four straight days of bundles.
I really think the problem IFK will have is there is no real headlining game there. It's just two steam indie games I never heard of. If they had a game like Dustforce, I think it would be more compelling.
Anyway I just built my bundle. I didn't want PAM or Diamond Dan but at the price of 75 cents, I decided I better in case Steam has them as a summer cheevo for the Summer Sale.
You know you have a problem when you bought a game just on the sole purpose of maybe it will be included as a prize achievement in the summer sale
. Although it was for charity so I don't really mind.