HD Radio is a great way to upgrade your car's radio, since you get better-quality FM broadcasts and your favorite AM talk show sounds likes it's on the FM band. The only catch is that you need a head unit or home receiver that's HD-Radio capable. At least you did until Visteon's HD Jump (set to retail between $200 and $250) arrived on the scene.
The HD Jump is a small transportable HD Radio receiver that can be used in the car or in your home with an optional dock. It mounts on top of your dashboard or wherever's convenient, really. The large monochromatic display shows station information, song titles, and the like, and it lets you select between multicast HD signals (extra stations on the same frequency) on stations that that are actually using them (still a rarity). It has an FM-modulated output, but that won't give you the audio benefits, so better to use the auxiliary output and plug that into the aux input of your head unit.
Even better, the HD Jump also has its own aux input, so you can plug your iPod or other portable audio device into the it and use its FM modulator to broadcast the signal to your car's in-dash receiver.