Premium Clear TPU Flexi Soft Gel Skin for Apple iPod Touch 4G, 4th Generation, 4th Gen, Satin Tinted Back
I've got a 4th generation iPod touch and this fits it perfectly. The gel feels like it adds some grip while not being a dust magnet. The only issue I have with it is that it makes the volume buttons hard to push. The power button on the other hand is still easy to push.  I don't have a dock so I can't comment on that, but the skin does not block the connectors at the bottom of the iPod in any way.