This is the Targus RemoteTunes(tm) for iPod. I got it from XSCargo, where they currently have them available for CDN$9.99.

Its guts include a transmitter and receiver pair. Even considering I don't have an iPod to use this with, for $10.. I'm not arguing.

The receiver has:

• HiMark RX3310A [20 Pin SSOP] - UHF ASK Receiver
• Microchip 12F675 - 8-bit PIC Microcontroller

The transmitter has:

• Microchip PIC 16C505 - 8-bit PIC Microcontrollers
• EPCOS R 800 CHT4 - Crystal

The receiver and transmitter both have some unused pins on them:

Receiver (Base):

• J: ICSP Data 
• C: ICSP Clock
• V: VPP / !MCLR
• G: Ground
• +: 3.3V from iPod

    PIC Pins:

1. Power (Vcc = 3.3V)
2. ?
3. (Something to do with the output jack)
4. VPP (Programming Voltage) / !MCLR (Reset)
5. Data (From HiMark Pin 8)
6. ICSP Clock
7. ICSP Data / Serial Transmit
8. Ground

    HiMark Pins: (Pages 11-12 of Datasheet. Pins I especially care about are un-italicized.)

1. Oscillator 2 (From Tunable Coil)
2. IF filter output
3. Comparator input A
4. Comparator input B
5. Comparator offset adjustment
6. Ground
7. Ground
8. Data (to PIC Pin 5)
9. Disable
10. Comparator input C
11. Limiter Input
12. Limiter Feedback A
13. Limiter Feedback B
14. RF Amplifier Input (Virf)
15. RF Amplifier Ground (Vee)
16. RF Amplifier Output (Vorf) 
17. Mixer Input
18. Power (Vcc = 3.3V)
19. Power (Vcc =.3.3V)
20. Oscillator 1 (To Tunable Coil)

Transmitter (Remote):

• J: VPP / !MCLR
• C: Serial Programming Clock
• Unlettered: Serial Programming Data
• G: Ground
• +: Batteries (6V)

    PIC Pins:

1. Power (Batteries)
2. ?
3. Play/Pause Button (Center)
4. VPP (Programming Voltage) / !MCLR (Reset)
5. Volume Down (Bottom Left)
6. Volume Up (Bottom Right)
7. ?
8. LED
9. ?
10. Crystal?
11. ?
12. Serial Programming Clock / Back Button (Top Left)
13. Serial Programming Data / Forward (Top Right)
14. Ground 

See also:
Apple iPod Jack Pinout - Explains the pinout and protocol for 2nd and 3rd Generation iPods.

(iPod is a trademark of Apple Computer, Inc.)