I have this thing where I like collecting 
original parts of things or autographs.  I have a 
tiny piece of the Titanic sitting on my 
bookshelf.  I have a drawing from the original 
publication of Winnie-the-Pooh.  Nearly every 
single CD I own has been signed by the band.  
(Granted, I mostly like small-time performers, 
major popular bands would be a lot harder to 
get...)  I'm a big Anne McCaffrey fan, and about 
1/3 of my AMC book collection is signed.  I'm not 
particularly interested in the Titanic or Winnie-
the-Pooh, but the opprotunity to get these things 
turned up, and my mind went "Ooooooh!  Neat!  
Shiny! I want!"

Enter the anime addiction... ^_^  Since, say, 
getting an original drawing by the artist that 
created the manga for my favorite show(s) is very 
near impossible, what can you do?  Then I met a 
cel collector, who showed me pretty IY cels... 
Heh heh, haven't looked back since.  And I have 
to agree with the previous poster who mentioned 
the thrill of seeing your sell on the screen for 
the first time.  "I own that!"