You can do quite a few things here actually. Apple takes pride in helping out their customers even if it's not covered under warranty which in your case might be the reason because batteries are not usually covered.
See if one of the nice managers in your local apple store can assist you, if not write a letter to the DM... wait about 10 business days and you'll get a replacement for sure. (well approval for one)
Second thing you can give a shot to is extended warranty which you might still have on your ipod. Go to apple.com and you can input your serial # to see the stats on that.
Thanks dude! I know just where to go!