Battery usage
Lithium Ion Batteries like to be used on a steady basis, but they donßt really like complete discharges.
There lifespan is counted in cycles, usually around 300 to 500, depending on the strength of the used cells. One completed cycle is a full drain of the battery. If you drain it only half way through (50%) e.g., it´s half a cycle. When you keep it attached to the outlet, the slow drain of 5 % in a couple of days is 5% of one cycle only.
So if you always drain the battery right to its end, you are alyways using a complete cycle and therefore you shorten the battery life much more than you would be using it in your needs, like one hour here, replug, one hour there, replug.
Keep it plugged in, when you don´t need the mobility, and use it when you need it. Don´t discharge it completely for no reason. You don´t need to recondition LiIon batteries, they don´t like it very much.
Same goes fo the iPod, it´s using the same technology.