My best Game Boy memories:
I remember first playing the now legendary Tetris and Dr. Mario on my friend's Game Boy at his house.
I remember marveling at Wario, the evil version of Mario, on a kid's Game Boy on the grade school playground. You could get a hat with horns and break blocks!
I remember not owning my own Pokemon yet and riding on a five hour bus trip with a friend who had it. I couldn't delete his save, of course, so I started, played the full five hours, and then lost my first Pokemon forever.
I remember when I did own my own Pokemon, after catching 145 or so I one day turned on the system to see "Your save file has been corrupted." If this hadn't happened, I'm sure I would have played every generation, but because of this I never touched a Pokemon between Red and FireRed.
I remember beating Link's Awakening four times, the most I've played any Zelda game.
I remember printing out my Link's Awakening photos on a Game Boy Printer.
I remember how I wasn't really good at Super Mario Bros. until Super Mario Bros. DX. Those challenges took me from n00b to pr0.
I remember playing epic amounts of the rumbling Pokemon Pinball. PIIIIKA!
I remember making fun of the GBC Perfect Dark with a friend when the enemies screamed full phrases after death.
I remember many, many, many high school lunch periods of hooking up four GBAs and playing Advance Wars and Four Swords.
I remember hooking four GBAs to a GCN and playing Crystal Chronicles and Four Swords Adventure (the only game I've ever needed to form a contract to keep all the players from quitting with rage at each other). Both those games are easily in my top multiplayer experiences ever.
I remember playing 2-player coop GBA Doom on a bus trip and punching a cacodemon to death.
I remember finally playing Metroid II, the last of the Metroids I beat. The music was awesome!
I remember throwing my GBA in involuntary primal terror when a bee landed on my arm while outside playing Boktai. The GBA landed screen-up.
Last GBA game I ever played was Drill Dozer.
You were awesome, Game Boy!