here's a pic of the front of our robot showing our ball control mechanism... i don't want to share all of it's secrets... but yes those are rubber bands on the roller. It works pretty well.
http://www.oregonfirst.org/wp/wp-upl...6-DSC_3468.jpg
you can see video of it in action at the Oregon regional here
http://frcstream.com/main.php (click search for events, event name: Autodesk Portland Regional - 2010)