Collect in-game? Well, my Juggernaut collects Cybernetic pieces. There are a few sets I don't have all the pieces for but well over half I have collected all the pieces. Recently finished collecting Series 505 Cybernetics. I think once I have them all, I'll deck him and his companions out in Cybernetic pieces and still have some rares to give to my other toons and their companions to wear. There are quite a few of these but I'm an avid collector now. Not really sure what got me started. Just bought some off the GTN one day, I guess, and it kept going from there...
Do you mean stuff like that? Or do you mean other things?