Knowing people in the music industry and the amount of shows I've attended in the last year has led me to collecting guitar picks. I view them as a form of art. Most artists have their own signature guitar picks, and they're a trip to catch at shows. It's also a plus when you personally know bands and can ask before/after a show for picks. They also change up from year to year so you really never get the same stuff. I have about 80 or so picks, 65-70 Unique. Bands such as Shinedown, Puddle of Mudd, 10 Years, Theory of a Deadman, Seether, Halestorm (know em personally, so have about 20 picks from them), Stone Sour, Sevendust, Bullet For My Valentine and the list goes on and on.
My personal favorite (besides Halestorm) would have to be a Corey Taylor Stone Sour pick that I caught earlier this year. He flipped it out into the crowd, and it fluttered right down into my hand.
I also have a smaller collection of drumsticks, one of which was from Mike Portnoy when he was with Avenged Sevenfold last year. A guy who was standing behind me offered me $100 cash for the stick after the show but I turned it down.