I just got the iRiver AFT 100 FM Transmitter to use with my Creative Zen Micro and I have to say it is great.

Thanks to the great design of the rx8 I used the 2nd power slot that is hidden and passed the wire to the cupholders where my Zen sits.

The iRiver is a great tranismitter and I live in a metro area.

HEre are my pros and cons
Pros:
1) Cost Effective, for $35 this is a great solution to get your Mp3 player going.
2) works with ANY audio device that usues standard headphones
3) Auto Shut off when it does not get a signal.
4) Small and does not need a battery plugs right into the power from the car.
5) No static in playback
6) allows you to broadcast over ANY station you wish.

Cons:
1) Not hardwired, cant control Mp3 player with steering wheel.
2) Not for audiophiles.

I got this so on the long trips i dont need to burn that many cds and im very happy with it. Just wanted to share.