art
      books
            Douglas Adams
            Dave Barry
            Arthur Conan Doyle
            Martin Gardner
            J. R. R. Tolkien
            P. G. Wodehouse
      computer graphics
            3D
            animation
            web
      movies
            action
            comedy
            fantasy
            film-noir
            sci-fi
      music
            classical
            pop
            rock
            techno
      video games
            Nintendo
                  action
                  adventure
                  puzzle
            PC
                  adventure
                  FPS
science
      mathematics
            puzzles
      nature
            hiking
      physics
            astronomy
            cosmology
      technology
            computers
                  graphics
                  Internet

I'll update this list whenever I do.