I just picked up the BG-E7 grip today, and the 7D feels like one huge heavy camera now! (In a good way!
In the few weeks I've had my 7D, I've customised it quite a bit. Direct focus point selection on the joystick (love this!), playback on the centre set button, I've set the DOF preview button to toggle between single and continuous focus depending on the current mode, changed the info button behaviour, set back button focusing on the * button (easier to get to), removed the auto focus point focus modes from the focus selection options (just single point, single point expanded and spot available), slowed the focus tracking sensitivity, set the MFN button to bring up the VF electronic level, set independent focus points based on camera orientation and memorised some favourites that you can easily toggle between your faves and the centre point, and changed a bunch of other custom functions I can't remember right now.
I really like the level of customisation available. I also set up a variety of setups on the various C modes on the mode dial which are really useful.
Loving the 7D so far!