Iphone off button not needed
If your iphone's off button is stuck or broken, you can still use all the functions of the phone. To turn on the iphone, you can just use the home button. What you need is just an application that turns off the iphone. Unfortunately Apple does not permit any application to do that, but if you jailbreak your phone you can install an application called PowerIcons for free. (launch Cydia and do a search for Shutdown.) But be careful. PowerIcon will give you four choices: shutdown, safemode, respring, reboot. If you're running your iphone and you press shutdown, it will turn off your phone immediately. However you will not be able to turn it back on with just the home button and you will be carrying a brick. If you do this accidentally, you can recover by plugging your iphone into a power source using your cable. This will turn on your iphone on again. To power down use the respring option. This will restart the springboard and assuming you have a password protection enabled it will ask for your password. Press cancel and the phone will timeout and powerdown. A bit kludgy, but you'll be able to use your iphone without the off button. Hope this helps.