I like it. Of course, I like Christopher Lee in anything.
Very good, though perhaps instead of Fred they should bring back Karl, Homer’s one-off assistant (in the episode in which Homer grows hair and gets promoted) voiced by Harvey Feierstein – that guy was pretty scheming, and he was even more openly, flamboyantly gay than Smithers. A love triangle sub-plot, anyone?
I definitely second the death of Hans Moleman. He’s just depressing, and I don’t think he’s funny.
Of course, in keeping with the character, he’d have some intensely pathetic death-- Getting a letter bomb on valentine’s day after thinking someone cared enough about him to send him something.
Manner of death is important, eh? OK, try this: Smithers finally “comes out,” and tells Mr. Burns that he’d give anything to be his lover. Burns thinks about it for a second, and then shrugs and says "Oh, why the hell not? It’ll be the most action I’ve had in decades. But I insist on being the ‘top.’ "
Cue romantic music and a parody scene in which Burns and Smithers run through fields and do all kinds of other stereotypical couple-in-love stuff. As the sun sets, Smithers carries Burns over the threshold of Burns’ mansion.
The next morning, Smithers is feeling ill, so he goes to see the doctor. Remember that episode where Burns learns that he has every disease known to man, but he hasn’t died because they’re all in balance? Well, Smithers has just contracted every sexually-transmitted disease known to man! But he doesn’t have any of the non-STD’s to balance them out, so he’s doomed.
Upon learning this, Smithers becomes morose and asks the doc how much time he has left. The doctor checks his watch and says, “I’m surprised you’ve lasted this long.” Smithers screams, and then he decays away to dust, just like that Nazi guy at the end of Indiana Jones and the Last Crusade.
Later, the doctor walks into Burns’ office and hands him a Zip-loc bag containing Smither’s remains. Burns falls into a suicidal depression and, deciding to go out with a bang, he tries to cause the nuclear reactor to explode. Homer stops the meltdown (through dumb luck, of course) but Burns ends up getting mutated into some sort of grotesque inhuman freak, which escapes into the woods.
No one’s mentioned Patty and Selma? Of course the likeliest death there is lung cancer . . . not entertaining enough . . . Hey, did they ever out Patty as gay?
Yes, she’s a lesbian (which explains why she never showed interest in men like her sister). She was outed this year when Springfield legalized gay marriage.
Except MacGyver…which is almost understandable, really; aside from the voice, and assuming he keeps his shirt on, he could pass for a butch lesbian. 
Who would I kill?
Eh, I’d just have Lisa set up a series of Buddist prayer wheels, then rip off The Nine Billion Names of God. Poof. No more monster.
“The Martyrdom of Ned Flanders” would be a concept worthy of its own thread . . .