Languages. Operating Systems. Compiler Optimizations. Meta-foo. Python. Haskell. Isabelle. Coq. BF, Unlambda, etc. Purple Toupee. And more lately: IDA. OllyDbg. Pin. Program Analysis. Although, I still have a weak spot for languages.
Half an MS in CE. Many many hours writing C, wishing I was writing in a yet designed language. University -> Start-up -> Small Company. Java rubs me the wrong way. I like C and Python (and Haskell, when I’m not actually using it).
@dionthegod on Twitter.