Get it while it's hot. You can pay whatever amount you want and get Psychonauts, Amnesia, Limbo and Sword & Sorcery. If you pay $8 (shifts depending on the average amount paid) you'll also get Bastion.
Bastion is probably the best one out of the bunch I've played so far (haven't tried Psychonauts yet). The visuals confuse me a lot and get in the way of the gameplay though. Amnesia was a pretty big letdown after all the praise it's gotten. I didn't find it very scary and the plot fails to grab me. Limbo you will appreciate a lot if you enjoyed Another World/Out of this World. Sword & Sorcery is... really not my thing at all. Overall it's a pretty good deal though.