The GameBoy is the grandfather of all gaming systems. There had been ones before it but none of them did it like GameBoy. The GameBoy was actually somewhat comparable to a game console and was a lot of fun.
The GameBoy Color
This one is pretty self explanatory, it's a GameBoy... in color.
The GameBoy Advance (SP)
I like the gameboy advance and the Gameboy Advance, But I certainly don't think it's Nintendo's best system. Still, I got a GameBoy Advance for free and enjoy playing it a lot.
Thats part one of Nintendo's Portables, check back soon for part two.