The Venturi Mini does some pretty cool things that other basic kits don't::
-Stream audio from a Bluetooth device to the Venturi Mini, which converts to FM for your radio
-It can also transmit status messages and alerts to your radio's display via RDS (including caller ID)
-Phonebook access/ctrl via the car kit's controls
-Handsfree calling, uses built in mic, and incoming audio is broadcast via FM to your car's stereo (consider the security implications of this before phoning your bank manager, mistress etc.)
-Also has charger connectivity (I think via USB out-of-the box, adapter may be necessary), and wired audio in/out
Negative's I've read, but can't confirm:
- iPhones dont work with it
- Charging is restricted to 500ma 5v(this is pretty reasonable tho and conforms to USB spec)
- The unit connects directly to cigarette lighter, and the close coupling can make fitting it a bit awkward in some cars.
It's not the newest piece of kit around, but it's well worth a punt at 39.99 - typically selling around £50 elsewhere. I've seen mostly favourable reviews.