[Fixup]

Some programs kill battery, this is not a full list:

Opera
Internet Explorer
QuickGps
Biotouch
OMC
Sensorlock
AlbumSearch
AudioManager
Skype
Fring
Windows Media Player (even not playing anything)
Garmin
......

These are good programs that you can let them run without impact on battery:

Jbed java midlet manager (all other midlet managers suck)
Opera Mini
Gmail (older than V2.0)
Xten Lite
ImapPusherService
TomTom (when in background)

Go get the free FdcSoft TaskManager3.1, then you can see which programs are running and using lots of CPU. acbTaskMan can even show the history of CPU usage.

Bottom line: smartphones are always on even when the screen is black. Many programmers do not follow the guidelines of putting their programs into standby mode or use too much polling instead of push and thus use too much CPU and thus battery. You must close those offending programs after each and every use to ensure good battery life.