As always, you can pay the minimum for a few games or beat the average (~5aud) for all of them. Either way you'll still get the games which are released later.
So far the games are:
Bag it, R Type 2, Aralon: Sword and Shadow, The Cave, The Room Two (Highly recommended), and Carcasonne,
More games will be added later on.
Edit: as mentioned below, only bta will guarantee you the future games apparently.
Referrer receives $11 AUD in Wallet Credit for the first 30 brand new subscribers that signup for Humble Choice after clicking on a referral link.
The Room Two too. :p
Just a note, unless they've changed it again, for the past few months you don't get the games released later unless you best the average now. However, even if you don't beat you can add money later, and they lock in the average for you as what it was when you first purchased.
Really? Good to know. Didn't buy the past few since I've owned most of them.
This is worth it just for Carcasonne.