How often do you re-read the books you own, or put a CD in the player? If the answer is, like it was for me, "barely ever", then you should clear them out and make some money from it!
I've been inspired by blogs and youtube to make my room more minimal. So I donated, binned and sold a lot of my possessions, and now I'm down to what I really need and use. Having a clean, spacious room feels great!
As a huge musical theatre fan, I had loads of tickets and little leaflets i picked up, which were cluttering up my room a bit. So I chopped them up and concentrated them into a collage for my wall, eliminating the clutter and making something pretty!