I have a 3rd generation iPod which is a few years old now. It has been great. I use it to listen to music going to and from work and as a pretty sweet external hard drive. Recently, my battery power has been slipping away quite fast and last week it seemed to be able to hold a charge for no longer than 30 minutes. I think it's the age of the battery combined with the freezing cold outside.
To fix this, instead of buying a new iPod, I bought a new 3G iPod NuPower battery from Newer Technology. When it arrived on Monday, I sat down, watched the instructional video, and installed the new battery myself.
The installation went well. Getting the iPod open was much more difficult that it seemed from the video. I really had to pry that thing open. Once I did get it open, though, putting in the new battery was a sinch. So far, everything seems to be working quite nicely. I never use my iPod for more than an hour so I don't know how long the power will last, but it has not died prematurely yet. The case is a little wonky on one side where I was prying it open, but not very noticeable. Still 100% functioning.