If you travel a lot and don't have a line in for your car stereo then I highly recommend the Itrip and the Belkin Tunedok (it is a holder for your Ipod that fits into most cup holders).
I had nothing but problems using the iTrip. 'Course, that was the 1st gen and I was living close to Cincinnati at the time (radio towers).
I recommend getting the in-line remote. The 2nd gen remte was pretty much defective across the board, but when it did work, it was very, very convenient.
I'd be steppin' campus with the remote blingin' the lapel of my leather. Some schnookie be like "Yo! You got a Pod?" And I'd double-ply "Yea, jes lemme reseat the remote connection in my pocket here and I'll show you how it's done."
Buy a case. I just bought one of the new 20 gigs with the click wheel and I passed on a case because there weren't any out specific to the new generation. Less then a month later and it look likes a feral squirrel raped my iPod. I don't really give a fuck as long as it works, but I thought you might want to know.
i ordered an iskin, so hopefully it'll be in sometime this week, but yeah, you're gonna need a case (in fact, i'd order an iskin now, cause supposedly the demand on them is HUGE and shipping could take a while). I bought my ipod last week and haven't even taken it out of my bedroom and the thing is already scratched up like amofo.