Any and all legend of Zelda games (I particularly enjoyed The Minish Cap). GTA advance, metroid fusion. Advance wars (all), Mario and Luigi superstar saga is excellent. Don't forget final fantasy tactics and Fire emblem games too! Oh can I ask what slot 2 card you got? I've been thinking of getting one myself (for the reasons above) but I can't really find much information on it... infact the only card I've seen is the EZflash 3in1 but I already have a slot1 card...
The Fire Emblem games are the best ones in my opinion But I just use emulators instead of my GBA anymore
hmm here's some of my favorites: Castlevania Circle of the Moon Harvest Moon Friends of Mineral Town Any Final Fantasy games (tactics advance, dawn of souls, 4, 5, and 6) Kingdom Hearts Chain of Memories the Megaman Zero series Mario and Luigi Superstar Saga (<--awesome RPG, im replaying it right now) the Dragonball Z RPGs (Legacy of Goku 1 and 2, Buu's Fury... well actually the first legacy of goku sucked =\) Golden Sun and Golden Sun the Lost Age all of the pokemons Zelda Minish Cap (and you might want to grab a link to the past while you're at it!) Sword of Mana Tales of Phantasia (well snes version's better imo) Breath of Fire 1 and 2 Grand Theft Auto Advance Fire Emblem Mario Kart Super Circuit Sonic Advance 1 2 and 3