Even tough the iPod is a nice piece of HW, its FW isn’t as powerful or as flexible as I believe it should be.
A simple example: it just doesn’t play OggVorbis files. I wrote to Apple’s support site asking when they were going to update the firmware to allow such an elemental task. More than one year has passed by, and an answer I haven’t received from them.
A couple of days ago I installed rockbox in my iPod mini, and new life entered my little blue music box. I recommend every iPod owner to explore rockbox: http://www.rockbox.org/