I used to have a Belkin TuneCast II for a couple of years, before I had an iPod - it was good, but not obviously any good for charging.
I bought 5th gen iPod recently, and we went on a long road trip this week, so I took the chance to buy a Griffin iTrip Auto (like this)
Having used it for the week, I can say that the sound quality is great, it is ridiculously easy to use, and charges the iPod.