I've been rotating some emotional Simpsons wallpapers lately. My last one was the final scene from "Mother Simpson", with Homer sitting on his car staring up at the night sky. That is one of, if not the, saddest endings to a Simpsons episode ever.
This one, however, comes from the end of one of my favorite episodes, "And Maggie Makes Three". You probably know that already, since I did submit a deviation a few months back called "Do It For Her"... anyway, it's my icon here and my current default LJ icon, just because I love it so much and I was glad to finally find a screencap of it.