What could be pulling down my battery over night other than the obvious things?

there are several things that can drain a battery: if the battery is more than a couple of years old and has been dead multiple times, it may be sulfated to a point that it will not charge, it is best to have a battery charged off the vehicle and tested. also any number of computers or modules on a vehicle can "stay awake" after the key is turned off. most are supposed to shut off after a few minutes. these are things you can't see, a seat module for example. a parasitic draw test can be performed to check for these kinds of problems