LifeSci and CompSci stuff. Health care IT. Gaming/Multimedia industry. Weird things. National Parks. Trains. Developing useful s/w. Drawing. Woodwork. Soccer, baseball, hockey, volleyball, biking, canoeing, running. Animation (traditional N/A, CG, anime/manga). Music (clarinet/piano[sort of]/guitar[sort of]).
Pretty much anything. White noise to absolute silence.