This topic deserved a bump, I encourage everyone who hasn't taken a look at the site, do so now. If you want an invite, just ask one of the over 40 people who have already joined the Blockheads group. Since you can't actually view the group without membership, here is a short list of some of the members who you can get invites from. Some of them only post on the RTB forums.
astro
Badspot
Bleh
Ephialtes
FrozenDragon
Gmp
kheyre
Mocheeze
Moose
Nitramj
Otis da Houskat
Packer
Pload
Resonance_cascade
Rotondo
snotface
Spaceomega
Spation
Wedge