Car CD changers

Sony CDX-GT520
The Sony CDX-GT520 is a decent option for those wanting a reasonably priced stereo to play disc-based audio. While it does support HD Radio, it requires the connection of a clunky add-on module, which is almost more trouble than it's worth.
Specs: Radio / CD / MP3 player, Radio tuner, CD / MP3 player, Audio line-in, Audio line-out, Subwoofer output, System components control bus

Kenwood KDC-X890
The Kenwood KDC X890 is a capable head unit that supports a broad range of audio formats. Voice indexing helps counteract awkward manual file selection, although the system's claims that it measures car performance are dubious.
Specs: Radio / CD / MP3 player, Radio tuner, CD / MP3 player, USB, Audio line-in, Subwoofer output, Rear channel output, Front channel output

Kenwood Excelon KDC-X790 CD/MP3 Player

Blaupunkt Heidelberg CD52 | CD Receiver AM/FM CD Receivers

Eclipse CD2000 CD/MP3 Player

USA SPEC SCD-VETTE 5 - CD changer
Specs: CD changer, CD changer

Pyle Audio PLTD163 In-Dash DVD/CD/MP3
Specs: Composite video/audio input, Composite video/audio output

PYLE PLCD23A - radio / CD player
Specs: Radio / CD player, Radio tuner, CD player, Audio line-out, Audio line-in

Jensen CPM510 - radio / CD player
Specs: Radio / CD player, CD player, Audio line-in

RCA RC128 - radio / CD player
Specs: Radio / CD player, Radio tuner, CD player, Audio line-out