Will GM for Beer
Don't Rest Your Head is my go-to for horror. It plays beautifully in PBP and is designed primarily for short games (you have to really tweak it to make it play ongoing adventures). PDF is like five bucks on drive thru and the rules summary is one page. Easy to pick up, easy to run.System TBD . . . Any interest?
I would be down for that in a heartbeaat. Of the others, I'd play SWA, but probably not so much with the D&D.