Well I thought this would be a good place for people to post up what hand held systems they own, what games they own - and thus we can see if we can have some multiplayer fun - from memory I know there's some mario kart fans out there.

so I'll start off:
nintendo DS:
advanced wars duel strike (there is a mode on this which can do multiplayer with only one card)

FFIII - not really any here

Heroes of Mana

I've got a PSP. No multiplayer games yet though. I got Loco Roco though :D

I've got a DS with Mario Kart, quite happy to give anyone a race or a battle. I also have Pokemon Pearl, but I think I may be alone on that one (and besides, my team sucks at the moment, all my good 'uns are on Ruby :P). I also have FFIII. Should have Bomberman with me soon, and that's a one carder I believe. Would be great fun to have a match on that!