In a 3e game a couple of years ago, our low-level party got into it with a couple of heavily-armed and -armored baddies that had been waiting for us on the other side of a tiny stream. The headstrong fighter wades in, steps on some strategically placed caltrops, and is promptly waxed by one of the evildoers. At -7 hp and facedown in the water, his prospects were slim (we called it "the blue light special" - a small, glowing number appears above the body flashing "-7, -7, -7, ding! -8, -8, -8, need healing in aisle four!, -9, -9, -9, going, going..."). Anyway, our cleric hesitates a moment, then wades in to save his buddy, despite everyone knowing what would happen ("That's what he would do!"). He takes his AoO like a man, going down to 1 hp, and casts his cure. He then, sure enough, receives a critical hit along the order of a small nuclear device, taking the express train to meet his god. His sacrifice, however, gave the party time to finish off the villains and saved the fighter.
An appalled moment of silence ensued - this was our first fatality. Since we were way out in the wilderness, there was no hope of raising him. We buried both halves of him with honors, and erected a sign, written in the bad guys' blood, forever naming the creek "Ahkeem's Crack".
There really is something enobling about having your character die in the line of duty.