Bachelor pad

I recently moved into my very own room. Great! I as a kid I always wanted a room of my own, but now that I actually have one, I have no idea what to do with it.
Currently my furniture consists of a double mattress on the floor in the corner, a computer desk, an empty shelf, a TV, VCR and DVD strewn about the floor along with several piles of clean and unclean clothes. I also have an green and white checkered area rug in the middle of the room.
I have been trying to come up with good Ideas ,but being a male , I think I have a mental block when it comes to decorating. I was thinking of putting up Pearl Jam posters but I think that will just come off looking either like I'm hitting a mid life crisis at 25 or that I haven't grown up at all.
Anyway, I thought I might pick peoples brains and see if anyone had cool themes or ideas for a room that I could do "on the cheap". I'm sure I won't be disappointed!!!