Let me first start by saying that over the years there were a great number of things in addition to baseball cards that I thought would be fun to collect. You will either be surprised by some of these things, or not even bat an eye. I collected everything from TMNT (Teenage Mutant Ninja Turtles), G.I. Joes, Starting Line-ups, comics, pogs (I hope someone else knows what they are), Simpsons figures, WWF magazines, etc. Obviously all of these things were over the course of my childhood when every kid goes through phases of things they like.
As an adult, I have mainly stuck to baseball cards and one other area. I sampled trying to go back to comic books, and stopping by the local shop every week or two and buying only first issues of whatever had come out, bagging it and putting it away. That got boring in a month or two and I was done with that again.
The one other thing I still collect I have been buying for about 6 or 7 years now, and I have a decent sized collection of about 300 or so. To make things interesting I am going to leave this up to you guys to guess what it is. Here is your incentive to guess: The winner will get a double from my collection OR their choice of a card of their team or player. I have plenty of doubles from both my card collection as well as my other collection.
The one hint I am giving is that this collection is very specific, like a player collection as opposed to a team collection except of something else.