I'm not sure how much it amuses anyone else, but I usually find humor mileage in slightly archaic/formal word choice/sentence structure being used to talk about something normal or mildly absurd. (e.g. using words like "whereupon" and "thereunto" in a sentence about candy).
Péter Esterházy's short novel "Tizenhét hattyúk" (Seventeen Swans) is sort of this taken to the extreme. It is about the bleak life and sexual adventures of a frequently abused orphaned young woman who is working as a janitor, and it is written entirely in 17th century ecclesiastical Hungarian, often resulting in hysterical laughs. It is doubtful, however, whether the anglophone public will gain access to it in the reasonable future.
Reading the recent list of rationality quotes arranged by karma underlines the popularity of funniness, and being funny should probably be included in the pursuit of awesomeness.
My best guesses about characteristics of humor: If there's a word which makes the line funny, put it at the end. Phyllis Diller recommends that the word should end with a hard consonant (t or k).
If you can make a surprising statement extremely concise, there's a reasonable chance it will be funny especially if it includes an insult about an acceptable target.
Quasi-quote from Jim Davis, author of Garfield: "If I can't think of anything funny, I have one of the characters hit another." Any other principles of humor and/or methods for cultivating the ability to be funny?
ETA: The most recent thing that struck me as very funny-- how does it fit into the theories?