Thing 15 is a website called Memrise which has the tag line Learn Something New Every Day. It contains courses/quizzes which help you to memorise anything from the Kings and Queens of England to the Chinese characters which make up a restaurant menu.
I’ve given it a go but to honest I can’t really see what use it has in my professional life. I tried out the Kings and Queens test but I didn’t find the mems (visual or anecdotal aids to help you remember things) very helpful and I soon lost interest.
This apathy towards Memrise may be slightly due to the fact that I am already marginally addicted to Sporcle which isn’t quite the same but it does include lots of trivia quizzes although no way to help you memorise the answers. Using the two together could make me a quizzing behemoth but as Memrise doesn’t have an iPhone app (which I think is a great downfall) I probably won’t be pursuing that dream any time soon.