I haven't come up with any addictions though I go through obsessions from time to time.
Transformers didn't do anything for me but I had a frighteningly large collection of Micronauts (
http://en.wikipedia.org/wiki/Micronauts) in the mid- to late '70s.
Lego's were always in the house but once I went off to college I lost track of the several boxes (bankers boxes) full to the brim I had.
High school and through college it was comics and RPG's (table top, not computer). In there was a span of several years where almost all my free time was focused around Star Fleet Battles (
http://en.wikipedia.org/wiki/Star_Fleet_Battles). Every rule book, appendix, ship SSD book, scenario collection and related magazine was in The Binder of Doom.
Paintball came and went, especially when the most affordable field in the area closed down.
I managed to dodge the Warhammer 40K bullet. It's fun to play from time to time but I was gifted with an army so I don't have a financial investment in it.
For a long time, (and it still is in my life), the SCA (
http://sca.org/) was hugely important. I am still active but not to the extent I was.
Right now I have a lot of fun doing research on topics around mental health, mental illness, behavior, cognitive processes and concepts of self and group identity. It's fascinating, interesting sometimes useful and even allows me to be productive from time to time.
After all that I've realized there is one thing I have never gotten over: Books.
I've pared down my library when ever we've moved and I'm replacing some with electronic versions from time to time but there's something about the tactile experience of a paper book in your hands I'll never tire of. There are books I won that I will never get rid of, even though they're literally falling apart because of how they tie in to my life.
So, addicted to books? No. Irrational about them ? Sometimes. Certainly I am a bibliophile though.