We started off with dead reckoning and now we're using two rotation counters (just a wheel with magnets and a read switch) and it works really well. It still needs a little calibration and we're usually a few inches off target so we won't necesarilly hit the middle perfectly but I think we'll always hit something no matter how low our battery is. (So long as the brakes are up at the start of the match javascript
:smilie('

'))
Here's a (hopefully obvious) tip: Be prepared to have your opponent place boxes in front of you before auto mode.
What I'm really worried about at this point is what will happen if four robots all decide to run for the center during autonomous mode. We went to the UTC scrimmage at Suffield and saw robots interfering with their alliance partners during autonomous mode (one even managed to end up right in front of his ally's starting position). We also saw that autonomous teams, even if they didn't make it to the stacks had an advantage over teams that just sat there. Unfortunately the only really viable strategy seems to be knocking over stacks and fighting over boxes and I'm beginning to think this game might end up a little more aggressive than FIRST anticipated.