I plan to have Cingular Wireless install a speaker phone in my X when it arrives. I have had installed car phones in every vehicle that I have owned since I bought my Lexus ES 250 in about 1991(the 1st year Lexus came out). You can purchase the unit from the wireless carrier and they will install it. This is a must for those folks who use the cell phone in their car alot.
Most cell phone manufactures offer car kit for their phones. Check with you cell provider or search the web. I have been using the car kits for my last two phones. They work really well and are a snap to install, just plug in the cigarette lighter adapter and then route the microphone and I usually just stuff the speaker underneath the seat. What kind of phone do you have? I have two extra car kits for the Nokia 8290 as I switched phones if you have the same phone.
I bought a speaker phone setup at Staples that would attach to the aux power next to the "not an ashtray". It appeared to have a mic hole near the bottom, but on opening (had to be a safe cracker to get into the package) there was a little mic on a 12 foot wire and jack.
Putting the adapter into the power port was snug, all conversations produced an echo, and taking out the power adapter was difficult and dislodged the panel the adapter is in. The panel is now loose and will need repair.
Shoved it all back into the package and took it back. No problem returning, but it is a bad product. Stay away.
This could be a candidate for stupid things done to X thread.