Give this Bad Boy a run!
http://alpine.com.au/showItem.php?item_id=34
I have 2 of them (one in the Rex, one in the Landrover).
Full ipod connectivity and navigation (either via bluetooth or the ipod cord), will plug into the AUX at the back of your existing headunit.
Handsfree through the car speakers, with the mic at the top of the pillar....to be honest there's not much this little thing can't do...specially for how easy it is to install!
I picked mine up for $99 each...however now having owned them I would pay much more for them!
On ebay for $129 and free postage...worth every penny!
http://cgi.ebay.com.au/ALPINE-eX-10-...ht_1958wt_1139