If you’ve got an Android phone, download Easy Battery Saver so you don’t have to charge it up every 15 minutes. You can customise it so it keeps the phone operation to a minimum when you’re not using it, e.g. apps don’t keep actively downloading things when you’re not using them and the screen backlight can be made to go fainter below a certain battery level etc. You can also tell it when you normally sleep so it can go into a less active state at night. Great Stuff!
Update: I might have been a bit too gushing about this app from first impressions as I’ve now noticed a few bugs with it, i.e. even in Normal mode when you turn the app on it seems to turn your wifi on, bit annoying. Also there is sometimes a significant lag in turning the 3G connection on for some apps. Finally I may be imagining things but I’m worried that some text messages might have come in late since the app was installed. However my battery is lasting a lot longer!
Update 2: OK if you get the setting right then this is pretty decent , i still have the problem that the locked screen of the phone no longer always tells me I’ve got a text but the battery is lasting 2-3 times longer. The best way of doing it is to switch to custom settings but don’t allow the app to control the wireless or 3G networks.