Most recently, I've finished Yoshi's Island DS with 100's on every level. I've heard that there was a secret ending available for beating the game with a perfect score, and I wanted to see the new ending (there isn't

).
I usually try to complete a game to earn any extra rewards that the game has to offer. I'm more interested in storyline rewards rather than ones that affect gameplay, though. Gameplay rewards such as an invincibility cheat, the strongest weapon in the game, etc. are typically useless after the game is completed. However, bragging rights are a decent consolation if the game doesn't really have anything but was difficult to complete at 100%.
Jam it back in, in the dark.