Hot Wheels/Matchbox - collected these as a kid; gave them away. Bought a couple hundred between 1996-1998; gave them to my nephews. Still get a kick playing with my nephews.
Sports Cards - Football, baseball, basketball, hockey. I stopped buying them in '91/'92. I sometimes go through the collection and cull the commons. I can't believe how many players I have no recollection of.
Non-Sports cards - Movie-related like Disney, Batman and everything else that sucked that I got suckered into collecting. I suck. Virtually everything tossed into the recycling bin or off to Goodwill with the exception of Star Wars, BSG, and a few other sci-fi sets.
Fast Food toys - In a 3 year period I amassed a few thousand, mostly by canvassing flea markets. It was a sickness, I tell ya. It quickly
got to the point I was acquiring for the sake of numbers and not for what I liked about each item. I got rid of these incrementally.
Superhero and Spawn action figures - DC animated to my nephews, other superhero to Goodwill. A select few Spawn around in boxes, the rest, gone.
Comics - All kinds, boarded and bagged. I still have 10-11 long boxes worth, and not one I've re-read in 8-9 years. I'm a tree murderer.