I don't seriously collect anything, I have a pretty decent LP collection. My personal favourites are my Blues Brothers soundtrack LP and the Sinatra-Basie LP. Big Bad Voodoo Daddy's tribute to Cab Calloway is hardly a collector's item but. It's another favourite listen. Not a big MJ fan, but I did pick up a nice pressing of Thriller LP for a song. I'd collect watches if I had the funds. Pens too maybe, I prefer fountain pens to ballpoint, but ballpoints are maybe a bit more practical. Still, I have a couple of fountain pens I always travel with, and only write postcards and other correspondence with it.
I did, however, used to be a fairly serious coin collector in my youth. My Pa and I put together a nice couple of collections which ended up paying over a years' worth of my college.
Some of the other collections here are neat. Tube type communications devices? Not too knowledgeable but I have a '47 Philco cabinet radio with AM/FM/Police band and that thing fills a room with some of the warmest sound I have heard out of anything. Original speaker too! Wouldn't mind having a something-or-other made with Nixie tubes, not sure what would make sense except a clock...but that'd be too mainstream for me.
Cameras...my primary camera is a Nikon N2000 35mm SLR. What a fantastic camera. I can see the appeal.