That'd be pretty fun, come to think of it, for multiplayer that is. Given a specific game that has come out recently *coughsmashgpcough*, it'd be great to play it on a TV, with more than one controller.
Like, one person could use the gp32 for P1 (not the screen, just the controls), and player two can hook up into the ext port, and player three can hook into player two, etc... kinda like the gba, how the cords hook into each other.
I don't know how you'd get the tv hookup...
Maybe Gamepark can make a cradle or something that hooks into the expansion port. The cradle will have a video out (the yellow white red cord thing), and a place in the front to hook in maybe 4 controllers? Yes, 4 seems to be the standard now.
The video and controllers will communicate through the expansion port. There will be a cord that comes out the side that you plug into the earphones jack, which will be the source to the TV's audio, and there'll be another cord that you can plug into the wall, and goes to the dc jack of the gp32. The GP32's screen will be blank, until you push start or something, which will bring up a menu where you can adjust the tv's picture, like stretching, audio filtering, which controllers are plugged in, stuff like that. Actually, scratch that, that'll probably interfere with the running game. Seriously, if something like that really did exist, I'd get it. Probably because of smashgp, that'd be awesome on a tv.
This is only a dream though.
Edit: Here, I illustrated it:
http://drag.wootest.net/misc/gp32_cradle.png