Is there an extended life battery for the iPhone 4?

I have an old iPhone I plan on keeping for an MP3 player and am doing a few things to it (replacing the cracked back/battery) to return it to its former glory.



Since I'll be throwing in a new battery is there something out there larger then the 1420mah?

via iLounge Forums http://forums.ilounge.com/iphone/278786-there-extended-life-battery-iphone-4-a.html