Got a GameCube for the GBA player to play my Advance remakes of FFIV & FFI&II on. I've never bought a game for it, although i have checked out Twin Snakes and played a good deal of Mega Man Collection on it.

Nintendo DS I was indifferent to until I saw the poster for FFIII - Coming Soon in GameStop. At that moment I realized I was going to buy a DS, and waited until the DS Lite/NSMB launch.

PSP I waited even longer to jump into until Metal Gear Solid: Peace Walker was announced. Like the DS Lite, bought it when a new model came out in anticipation of the game.

As far as those two systems, I've gotten a lot of other titles but it was definitely those two that made me get it. Might just be a timing thing, since most consoles release a couple things I want for them eventually. PS3 was a timing thing as well, I got it in anticipation of GTA IV and MGS4 at the end of 2007/beginning of 2008.