I'd found a couple of RPG systems that are absolutely perfect for one-shots, actually. This seems an auspicious place to dump them:
AFTERSCHOOL ACTIVITIES - An after-school detention goes horribly, horribly wrong, and the coffee machine is your only hope of salvation. Also Eldrich Horror in a(n all-girl) boarding school. Has a pretty cool 'tiredness' mechanic, and was written and created by the /tg/ community.
Sagas of the Icelanders - a game about building a settlement in Iceland, with one player as a suspicious stranger and a harbinger of trouble. I've not played this one yet, but I picked it up in the Bundle of Holding and have been intending to try it out.
There's also a supplementary WoD book called "Mysterious Places". It's got some pretty cool ideas for settings for One Shot games, which could work in any setting, really. Heartily recommended, if you ever get a hankering to run a CoC, Fear Itself or WoD: Mortals game. Things like a seemingly bottomless flooded quarry, and a forest that may or may not actually be purgatory.
I'm looking forward to Pokethulhu - so many potential shenanigans to be had. I love the series' you guys do, the varying one shots will always be my favourite way to enjoy RPPR.