This is an old post, preserved for reference.
The products and services mentioned within are no longer available.
Here is another Atari 2600 Junior ready for a composite video output modification.
Future Was 8 bit Deluxe Composite Video mod kit (currently on offer at £10).
Atari 2600 Composite Video Mods for more examples, including the metal can modulator version of the 2600 Junior.