There are a lot of people that would be very happy to receive a check from Knuth for reporting a bug (those checks are rarely if ever cashed, for obvious reasons).
Donald Knuth no longer writes personal checks for finding errors in his books and code, though he still issues a credit for the correct amount at the (pretty sure it's fictional) Bank of San Serriffe [0]. The page I linked to also mentions that he will try to send legal tender to a bug-finder if she or he really wants it.
