It's a nice touch, having a little icon next to every DS game when you boot up the handheld's menu. Like the little animations you got to go along with your PS2 save games. Very cute. In honour of this nicety, GAFfer Stumpokapow has put together a collage collecting 1250 of the 32x32 pics. It's not every DS game, but if you're more concerned with completism than how great the picture is, you're very much missing the point. Full pic is at the link below.
More than a thousand 32x32 DS game icons [Stumpokapow @ NeoGAF]