The great G. Carlin has a list of people he could do without. Like guys who wear hats with a lot of little pins on them.
I like a lot of little pins. I do skewer my hat with them, but I also load up cardigans and pocketbooks and overcoats. I'm talking about baseball pins, mostly. I just bought a dyn-o-mite NY Mets Doug Mientkiewicz pin! Yeah, 16!
Baseball cards, I can take or leave. Sometimes I buy a pack. Then I leave them all over the place and step on them with muddy shoes or let the cat sweep them under the space heater. Got a book in an internet book swap and there was a cheapo Trot Nixon card wedged between the pages. I use it as a bookmark and as a constant reminder of what FEROCITENSITY looks like. Baseball cards also make handy coasters.
What I like best to save and savor are programs. That way I can go back and read them on a rainy day or a sunny day. Many of the programs were made by jerkwad interns and crammed with ads that are merely photocopied local business cards, but I love them just the same.
T-shirts and hats are nice, too, but that's an entirely different story altogether.