Phone (HTC/Cingular/AT&T 8525) has a standby life of about 6 hours..

[Syringer]

It seems to have just started pretty recently, but I can't go through half a day without having to recharge the damn thing..any tips on what can be sucking up the battery?

 

[George P Burdell]

Your battery's probably getting older.

 

[kedlav]

how long have you had the phone, and do you use good battery management practices (drain nearly all the way before charging)?

 

[bassoprofundo]

If it just started with no changes to your mail retrieval settings (push, etc.), no new apps installed, etc., it's probably just a worn battery. I ran into the same thing with mine when I had it after a year and am running into the same thing with my Tilt now after a year. I ended out just snagging a second OEM battery and keeping the original as a backup. It'll probably run you $20-ish, and assuming no app issues causing a major drain, you'll be back to your original battery life. Well worth it IMHO...

BTW... A hard reset will (obviously) clear any potential app issues if you're looking to isolate the problem, but you'll have to reinstall any addon apps and restore your data. If you haven't done so, I highly recommend trying some 3rd-party ROMS for the phone. More info at the XDA Devs Forums.