Well I've seen a number of dead Supermutants (always seems to be just the supermutants) go all "Flying Squiggly" on me. I take down a Supermutant and then when I approach to loot the body I suddenly see what turns out to be the body - except that it's spinning, swirling, and all mutated, stringy, spikey. Like his skeleton is suddenly at war with itself and trying to poke a random hole and burst out of his now stretchy rubber skin. At the same time he's hovering around in random directions - a little higher, a little lower, moving this way and that. If I get close enough to it I can actually hit E and open it up to loot it, but then it will just continue spinning and squiggling and float away randomly.
While it wasn't wierd or funny I had a cool random event. Just started a game and first thing I'm doing is heading to SuperDuperMart to load up with loot. Outside there's a random event taking place - several raiders fighting a DEATHCLAW! I let them duke it out until the deathclaw has finished them all off and has just a bar or two of health left. I empty my pathetic little 10mm pistol into it and it drops dead. I search the bodies and find... schematics (and IIRC the components as well) to make a Deathclaw Gauntlet. I, of course, immediately went back to Megaton and made one, then sliced and diced my way through everything for the next 5 levels or so - basically until I was running into too many things at once in encounters and I couldn't just one-shot them all with the claw anymore. Nice way to start a game.