Those dreamcast VMUs didn't weigh much. I don't recall anything cool going on them. Did Skies of Arcadia utilize it a little... hrm... Nintendo already copied the playable VMU things a bit with the GBA connectors to the GameCube. It was the only way to play multi-player in Final Fantasy Crystal Chronicles.
What I want to know is can I just carry the controller around and play mini-games on it then synch with the main console later?