When I was I kid I used to collect stamps and baseball cards, just like nearly every other American kid does. Then, about 3 years ago I started collecting US coin sets, mostly proofs from the US mint for my kids (they make great presents BTW).
As a lover of history and economics, coin/money collecting (numismatics) just made sense to me and now I go to the monthly coin show in my area and spend a few hours a week on Ebay searching for for interesting coins and paper money for my collection. Just this week I picked up something that reminds me of runaway inflation from the past. Its a 1923 - 20 Million Marks bank note from the Weimar Republic of Germany. Inflation was so rampant during the Wiemar Republic that people used these notes as wall paper.
Since I want to own a piece of history, I bought it for $1.75 from Ebay. Goes to show you, one man's wall paper is another man's treasure.