Reading maps. I want to take the Knowledge one day and not actually be a cabbie.
Also taking Geography quizzes. If anyone's heard of Only Connect (takes hard quizzes to silly levels) a four-part sequence came up which went Victoria, Edmonton, Regina, and you had to guess the last in the sequence. I instantly screamed "Winnipeg!!" at the television. I also learnt all fifty US state capitals, and can reel them off if you shout the name of the states at me. Also the Tube map. Name a station and I can probably tell you which line it's on. Useless knowledge.
I also have silly collections like: old tickets (bus, football match, train, you name it), stamps, old boarding cards, loyalty cards, foreign drinks cans, foreign coins and banknotes, and last year I had a copy of almost every single university prospectus in the country.
I also stare at the US immigration stamp in my passport at every given opportunity.