So I only saw this posted once, buried in another thread about battery usage, but I think this should be sticky, because I've gone from needing to recharge every 20-30 hours to only losing 10% battery per 24 hours with light usage (ie check email a few times, 20 minutes of calls a day, use for alarm and todo lists).
The solution seems to be to disable incoming beams (settings/connections.beam/Receive all incoming beams).
I've been on here for a while since the Mogul first came out, but I only saw one person mention in a few days ago. It's provided the most drastic battery savings for me beyond anything else. And who uses beams, now that everyone has bluetooth anyway?

I also have the normal stuff off like WIFI/Bluetooth/no push mail, but that did nothing compared to disabling beams.
It was annoying coming from a Nokia smart-phone that only needed to charge every 4 days to one that demanded my attention constantly. Last regret is now gone.

Oh wait, if they could fix that alarm thing not working when the phone is plugged in, that'd be great too!