The truth is, I have the attention span of a retarded hamster; so very few things really hold my attention for any length of time.
There are some exceptions -- I can read for hours (if it's a good book), I can write for many many hours on occasion (sporadic, but it happens often enough that I can get the occasional book out), putzing around on the computer, playing hockey, watching certain TV shows (no reality TV, thank you very much; if I wanted reality, I would have stayed married), or walking around at the mall.
Lately, I've been doing a lot of reading about string theory/superstring theory/M-theory, or whatever it is they're calling it this week. Fascinating stuff. The whole idea of six or seven extra spatial dimensions being curled up into some sort of minuscule Calabi-Yau manifold is intriguing. Of course, the main reason I'm researching this stuff is because I may want to incorporate some of these concepts into my own writing.
I recently finished reading Julian Barbour's "The End of Time," a wonderful book, and one which, I have to admit, I'm not entirely sure I have absorbed all the way. Mr. Barbour's premise, that time does not exist, is one which I instinctively want to embrace, yet there are things like distance and motion and music that tend to want to push me in the other direction. Let's just say I'm "uncertain," at this point.