Great thread! I love learning this stuff about you all!

Hmm, where to start?…
Language. Love it. Studied 6 languages (English --of course--, Russian, Spanish, French and with some Hebrew and Latin thrown in for good measure.) Alas, have probably forgotten more than I ever learned.
Related: I adore Stephen Fry.
Top secret: I transliterate things I don't want anyone reading into Russian. (ie., English words written in Cyrillic alphabet.) Bonus points for irony, because, if it is extensive, I get lost and don't know what I'm talking about either(!) (Works for writing down gift ideas though…)