I'm involved in 1-2 potlucks a week, and next week I'll be the host. We typically do national/regional cuisine themes, like New Mexico or Japanese or whatnot. I'd like to do something a little more abstract, but not so abstract that people don't "get" it. So far I've thought of maybe a color theme, but blue is impossible, green would produce too many similar dishes, etc. I was also thinking of memories, like favorite foods from childhood, but there's a reason we don't eat the things we ate as kids anymore. I was also considering eras, like the Great Depression (too depressing) or the 1950's (funny, but not actually tasty).