My wife has just discovered she's going to be getting a sizeable refund of the FICA taxes she was paying as a medical resident prior to 2005. Apparently a fairly recent court case has prompted the IRS to process refund claims from hospitals and the like. Though you cannot claim as an individual now (past period of limitation), you CAN claim through your residency or fellowship program.
Just a quick heads up - if you were a medical resident (or know someone who was) between the mid 90s and 2005, it is worth contacting your program(s) to see if you are eligible, and at least update your contact details with them. Can work out to a nice sum.