I don't think there is. I have been searching a lot of places and if you want a bigger batter... You have to get an actual bigger battery. I just bought mine today, will be here Saturday, and I think the size will be a small bump for the benefit that I will get from it.
I have read that with the extended battery on the droid x you can just barely squeeze the original battery door on it. However doing that puts some extra pressure on the back of the lcd
It's listed as extended life, for Droid 1 or 2, but its just 1500mh, I think the Droid 1 original battery is 1300 so on paper its just a 15% increase. Anyone tried it?