Is your iPod low on battery power ? If yes, send the iPod (with the battery) to Apple and they'll will send you a replacement iPod fitted with a brand new battery for around $65 as service charges. All your existing songs and video collection will obviously get erased.If that sounds too expensive an option, get an an iPod battery kit at half the Apple price from the market and replace the iPod battery yourself by disassembling the unit as explained in the following Youtube video.
Though it is not so difficult a task to replace the iPod battery at your home - if you not too adventurous, it's better to pay those extra bucks and get a new one from Apple.
If you iPod batter runs out of juice in the first year of operation, you can ask for a free replacement since the iPod 1-year warranty also covers the iPod battery unit. [via]
Related: Unfreeze and Reset any Apple iPod ?