The Memrise community (http://www.memrise.com/) are quite big on that kind of thing. If you're learning a language, you can browse through their community database of mnemonics or "mems" for inspiration, and are encouraged to create your own. Their site is also quite good as a spaced repetition tool for languages.
In about eight months or so, I will be one of those (hopefully not starving) students. I'll be moving out to London to live with my aunt and uncle in a rather nice middle-class neighbourhood, while I study and work to prepare for university the following year. They know a lot of the parents around there and suggested that I begin teaching small groups of 8-to-12 year old children for maybe an hour or two regularly, and charge their parents/guardians a reasonable sum per child. I would be teaching them math and science in all likelihood. Apparently word will get around quickly if I'm competent so I might have a substantial number of customers within a few months.
My questions: