I just have the griffin itrip, and it works great.
I ordered an "iTrip Auto" as soon as I bought my Touch last month. It's basically a cable with a cigarette lighter plug on one end, the Dock connector on the other end and the FM transmitter in the middle. The upshot is that you can listen to your iPod in the car over FM without draining the battery.
Pros:
+ Very clean design.
+ Black. I feel a little safer leaving the adapter plugged into the car. White cables are more tell-tale and say "probably an ipod in this car. time to smash-n-grab." (I never leave the actual ipod in the car, however.)
Cons:
- Line level audio is too soft.
Ended up giving the iTrip Auto to my girlfriend, since she had no problems using it in her car with her 3G Nano. I went back to using a cassette adapter but I'm back in the market for a car charger/FM kit again since we've replaced the factory stereo with a DVD/Navi (but no AUX in
)
Thinking about the
Universal iTrip Auto, which is very similar but plugs into the headphone jack and has a female USB port for charging any USB-chargeable player.