I was recently asked (by a surprising convert to the iPhone, you know who you are Bob!) about extending the battery life, so i sent him this:
>Turn off WiFi/Bluetooth when not needed
>Disable "push" and sync at an interval
>Dim the screen
>Only charge when <3% remaining (requires discipline that I often don't have!)
>Turn it off overnight!
>Turn off vibration for alerts/calls/games
>Turn off notifications
>Don't have loads of email/calendar/etc accounts on the iphone
>Disable 3G! (we seldom get proper 3G coverage in the UK anyway - outside major cities)
>Disable location services
>Decrease auto-off setting to 1 or 2 mins (from default of 5)
>Turn off "load remote images" on email
>Turn off repeating alerts for email/sms/appointments
I have found it better to sync large volumes (eg app updates) over Wifi than over Edge/3G, as the time is so much shorter the power drain is actually less...
Hopefully someone will find this useful…