I recently took up coin collecting. I've actually been collecting coins for a while, but I really got into it when I found a 110-year-old Indian head penny in the cash register where I work earlier this year. Also, just recently, my dad gave me a bunch of old coins he got when he was younger, but none of them are as old as my penny. I also have all of the state quarters that have come out so far and the first 5 of the presidential dollar coins (I've fallen behind on them so I might need to take a trip to the bank).
I'm also in to computer programming. My big project I'm working on right now is creating my own scripting language which I've dubbed OnyxScript (the name is kind of a long story). So far it's to the point where I've been able to use it for small, simple programs, like one where I type in a date and get back which day of the week it falls on, and one that analyzes the Pokemon type chart to see which types are the strongest and which are the weakest. In fact, I used the type chart script to create the more balanced type chart I talked about in this thread.