Delphi's Vehicle Diagnostics system works best as a tool for parents who let their kids drive the family car, as it shows the car location and will trigger an alert if the car leaves a proscribed area.
The TextBuster system makes good on its promise to bust text-messaging and apps, but paying hardware prices for what's basically a software solution is a hard pill to swallow.
The Kinivo BTC450 is a good and inexpensive choice for adding Bluetooth to cars with an auxiliary input, but it is short on features.
The Gogroove Smartmini BT is a multifunction audio bridge and hands-free calling device that performs only one of those functions particularly well: FM transmission.
The Sony MEX-GS600BT's App Remote function is not very useful without a dashboard mount for your phone, but everything else about this full-featured car stereo makes it easily recommendable.
The Automatic driving assistant helps drivers who know nothing about cars to monitor and boost their fuel efficiency with plug-and-play ease and a simple interface that even laymen can understand.
Although an interesting idea in automatically updated portable storage, the Automatica's functionality is easily duplicated on a smartphone.
The Pioneer DEH-X9500BHS packs in a remarkably wide range of audio sources for a single-DIN receiver, including some rudimentary app integration.
The Alpine CDE-141 won't blow you away with bells and whistles, but this entry-level car stereo gets the basics right at a competitive price.
The iMagnet Mount suction-cups to a car's windshield, and holds a smartphone in place magnetically.
The CarMD Vehicle Health System turns up very limited data compared with the cost of the device, and it offers few real features.
For iPhone 4 and 4S lovers, the Pioneer AppRadio 2 is possibly the best aftermarket receiver that money can buy. For Android users, the choice isn't so obvious.
Depending on the position and nature of your car's cup holders, the Satechi SCH-121 Cup Holder Mount is a reasonable alternative to windshield-mounting a tablet.
At less than half what you'd expect to pay for a standalone device, the PLX Kiwi Bluetooth is a great OBD monitoring solution for the Android smartphone-toting car geek.
The Grooveshark Bluetooth Car Kit isn't the best hands-free calling option and its app integration needs finessing, but the hardware is an easy way to bring Internet radio and smartphone audio playback to almost any car.
The SuperTooth Crystal is a simple Bluetooth car speakerphone, relying largely on your smartphone to do the heavy lifting, but it has a few tricks up its sleeve to make it easy to live with.
The Magellan Wireless Back-Up Camera boosts the functionality of the RoadMate 9055-LM and upgrades the safety and convenience of any vehicle with very little effort.
If you want easily accessible emergency services and like the idea of having a real person on tap to help you pick destinations, OnStar FMV may be worth a look.