Through out the years, I had so many different kinds of collections, they come and gone, some stay, few are making a comeback though. Here is a list of the collections I had through out the years, enjoy!
Teenage Mutant Ninja Turtles (now it's slowly building 
up again, mostly in comic book forms)
Pokemon (still got those magna comic books though, and bunch of binders of old Pokemon Cards, and some old video games)
Beanie Babies (it stopped now once again)
Garfield
Pluto
Yoshi
Sonic the Hedgehog (now in just comic book forms also)
Digimon
Power Ranger
Slug Bug Cars (still around)
Hotwheel Cars (sadly, no matter how hard I try to collect them, I keep losing interest on them)
Dragons (still around)
Seals n Sea Lions (my most widespread, popular collection, still going strong though)
Coins (slow now, but might build again, goody)
Comic Books (recent new addition of new kinds of collections, some of my past favorites are now in comic book forms like TMNT, Pokemon, Sonic the Hedgehog, to name a few)
Books (Animals, Harry Potter, Novel, Warrior Cats, and so on!)
Video Games (had different kinds of video games: Sega, Playstation, Gamecube, GBA and GBA SP, NDS, NDS Lite, Wii, and also NDS XL too! right now, just NDS XL and Wii only)
Star Wars (mostly Jar Jar Binks, when he was 1 of my favorite characters back then
Stuffed Animals (outgrew them, got tired of them overcrowding my room, and other reasons, so I had to get rid of them)
Transformers (I tried to go back, but oy peer pressure and other reasons made me quit)
Owl (I did try out for lil bit, but never worked out cuz, my other collections took over, and it just died out anyway)
Velociraptors and Komodo Dragons (again I tried but, no room and others collections once again took over, made them extinct ya know)
KeyChains (still doing good, got lotta of them anyway)