The DLO nanoTune is several accessories in one:

“Its got a powerful FM Transmitter that plays your nano’s music over any radio. It adds a built-in FM radio to the iPod nano. It boosts nano’s volume by over 25%. … It’s also a protective case with access to the iPod nano’s controls. nanoTune has a 30-pin connection so you can use it with your existing car charger or with your HomeDock (or Apple Universal Dock) to sync and charge your nano at home - and you never have to remove your iPod nano from the safety of the nanoTune case.”

nanoTune features:

* nanoTune plays iPod nano over your car stereo, your home stereo or any FM radio, anywhere
* nanoTune adds a Radio to your iPod nano with just the push of a button
* Listen to news, sports, talk, weather with nanoTune’s built-in Radio
* nanoTune protects the iPod nano with a clear plastic cover and protective case
* Headphone amp boosts nano volume by 25%
* Works as convenient desktop stand
* Saves nano battery life in iPod mode
* Advance and review tracks with nanoTune
* Positions the headphone jack on top of your iPod nano
* Works with Apple’s dock for iPod nano
* Never have to remove nano from case
* Works with any iPod charger
* Tune using scan mode or manual tune

Available at Amazon.

Source.