Tetris board game:
details here:
http://www.gamerhistory.com/forum/viewtopic.php?t=177
Microsoft sent me roughly half of a launch team 360... i'm still waiting for the other half.
Edit:
Who can forget the Official Microsoft POGs from the E306 invite?
360 Post-it notes:
Bunch of weird promo stuff here:
http://www.gamerhistory.com/other/