hopefully " named" souldgems are back in the game. That was the most fun for me. Regardless Bethesda always puts other fun stuff into the game to scavenge
If If collect something, it'll be nice, shining things to decorate my house (jewels, valuable objects and so)...well, that if I don't have to sell them in order to buy something else.
In Morrowind, I collected hundreds (probably) of books. I just loved coming back from a big, bad dungeon or quest and relaxing by reading books in my library. Book Rotate and Book Jackets were essential mods for me and I hope they put those things in Skyrim.