Pod Player (formerly MyPodPlayer) is a freeware application to carry on your iPod. You can play your music on any computer when you iPod is connected without the need to install any programs such as iTunes.
When launched, it will look for an attached iPod and when it finds one it will read the music database on the iPod. You will then be able to views your songs in a similar way as in iTunes (by artist, genre, album, playlist, etc).
You can now also extract songs from it. There are a few little extra features such as iPod Hacks, checking for duplicates etc.