not sure if anyone has mentioned picross - but if you like puzzle games and online play this is a must have game!
also - it is very cool to connect wifi and download all the old mario picross puzzles from the old game boy days.
Super Smash Bros = 5155-2593-8058 - bama
Mario Kart DS = 055-952-949-094 = bamads
Mario Strikers Charged = 030180 671963 = bama
Madden 08 DS = 055957 382093
Picross = 536989 319836 = bamads
Clubhouse Games = 5241-0781-1239
Wii games: Mario Strikers, Mario Galaxy, Lego Star Wars, Sports, Wii-Play, Mario Party 8
DS games: Super Mario Bros, Mario Hoops, Picross, Mario Kart DS, Mario Party DS, Crayola, Brain Age 2, Madden 08 DS, Clubhouse Games