Recemtly picked up a Nomad here and started doing some mods to it. Work done so far:

• enabled SMS mode (play Sega Master games)
• JP region mode (hold A when booting up)
• LCD swap with new 3.5" screen
• Modded battery pack with Lithium ion battery - 5+ hours gameplay
• new green power LED, turns orange when low
• s-video output

The new thing that I did today was add a controller port for player 1 (Nomad only has a port for P2). This means it is the ultimate portable home console. Here is the video of the first run:

http://www.youtube.com/watch?v=92thd3L04HY