halo was pretty good imo.
He likes Halo! GET HIM!!!
The most memorable ending in recent memory for me was when my roommate and I beat Metal Slug X for PSX. The game is riddled with crazy and humorous stuff, such as fighting while riding camels with laser guns strapped to their stomachs, and a end-level boss that randomly gets eaten by a killer whale after you beat him. At the end of the game, it turns out the general of the enemy army was in cahoots with aliens, so the last boss is a giant independace day mothership. The aliens betray the general, so while you fight the mothership the enemy soldiers you were killing the whole game show up and help you fight the aliens. When you finally shoot the mothership enough times, a random guy in a biplane crashes into it and destroys it! You kinda have to see it for yourself, but it's hilarious. If you see it at your local videostore, rent it for a weekend and beat it for fun.
Seriously speaking, my favorite ending would have to be Chrono Trigger, followed either by Final Fantasy IV or IX.
I want to see what the Zero Wing ending is like. Do you get to blow up Cats?