Lemme see here . . . (keeping it organized so i can remember)
Elementary School years (age 5 - 11, 1996 - 1992): Robots (in general, like from Robotech), GI Joes, TMNT (and had select toys present when watching said shows), Star Trek: TNG., computer games (father was in early programming, so was always a computer in my home. What can i say, was fortunate enough to start early ).
Middle School years (age 11 - 14, 1992 - 1995): Battletech (Mech info, stats, making my own, you name it), Exo-Squad, Star Trek: TNG (best Star Trek series ever imo), Battletech novels (got interested in reading late in life).
High School years (age 14 - 18, 1995 - 1999): Battletech (kept up with it, even though only played against brothers), Magic: The Gathering (started around Mirage, 5th, and Tempest, for those who know the game), Isaac Asimov novels (loved Foundation series and the Robot mysteries), Star Wars novels.
College and later (age 18 - current, 1999 - 2010): Maintained a few of the older obsessions, AvP/Aliens/Predator novels (quick reads but enjoyable), random anime, gundam and zoids models (during college to pass time), random science/physics concepts (rail/coilguns and some others), and some other sci-fi/fantasy oriented concepts/entertainment.