The topic I have in mind today will regard a recent hobby I had of collecting rare/valuable currency. It all began approximately a month ago when a silver dime was found in the cash register as described in this thread: http://teamliquid.net/forum/viewmessage.php?topic_id=55222.
Basically, ever since I found out about numismatics*, I've fervently raided and scourged every coin or bill I'd come across to find out if there was anything possibly unique about that particular piece of money. How far did I get so far? Well...
Coins
wheat pennies - ~30x (mostly 1950's, some from 40s and 20s.)
1961 Silver Quarter**
1959 Silver Dime**
Paper Money
1950b $10 bill
1963A $10 bill
1981A $20 bill
1988 $100 bill
1990 $100 bill
Most of these that I've collected so far are hardly worth over face value, but it's a start. Even though I'm hardly finding anything worth keeping, I'm sure that I'll hit the jackpot by the end of the summer. If there are any other numismatists out there, I'd be glad to hear more stories. I remember Hawk, a relatively new member once found an error*** on an early 1900's mercury dime (double dye) and got $200 for taking all of 10 seconds to rummage through his pocket change.
As for sites that have information about old money/error money, here is a good site that I've visited:
http://coinsite.com/
*Numismatics - the scientific study of currency and its history in all its varied forms (taken from wiki).
**Silver coins - from 1932~1964, the United States of America circulated dimes, quarters, and exclusively 1964 edition kennedy half-dollars with 90% silver content.
***Error Currency - Coins and bills alike circulate mint errors every once in a while. These errors come directly from a genuine manufacturing error, which is so rare that money with such errors can be worth many times their face value.