Soldato
The wife has just gone over from a call/text package to a call/text/data package and is seeing a massive decrease in battery life (and know she isn't spending time on the Internet).
I've turned off the Background Data setting, anything else I can do?
A few options that I can think of...
You could turn off account sync settings to stop the phone from automatically syncing with Google all of the time. It will automatically sync contacts, calendar etc
You can turn off background data sync (but the market needs it, however I just re-enable it when using the market). This prevents apps from using data at any time. (this one you have done already but I'm too lazy to delete what I typed)
You can decide when to enable 2G/3G to control how much "extra" battery usage it is taking to provide a 3G connection, you could put a toggle widget on the desktop or pull down power menu etc.
You could use something like Juice defender or Green Power Premium.
If you are using a custom ROM you could use SetCPU and create an overclocking profile of 122mhz min to 245mhz max for when the screen is off.
Turn down the screen brightness.
Install betterbatteystats and monitor what partial wakes there are.
Place the phone in Airplane mode before bed and then back to normal in the morning - the two noted packages can be scheduled to do that.
A few ideas.