right now my pins are on lanyards hanging from my closet door knobs.
A few years ago when I had several olympic pins I bought an embroidery hoop and stretched a piece of denim (from a worn out pair of jeans) over the hoop and attached the pins to that. Ive been meaning to do something like that for displaying my son's pins.
i keep my pins in pin collector "books" that can be bought at disney at the larger pin stations. it looks basically like a suitcase with a zipper on the side of the front. it has several "pages" made of a felt-like material where you can stick your pins in. it works great to display the pins and keep them safe, too.
I don't have a ton of pins, but I keep mine in a collector book as well. I like that I can add pages as I add to my collection. When it gets large enough (or when I have more room!), I'm planning on putting them in a shadow box to display them.