This is a great question.

Here are a few others of note that I obtained from http://www.mapping.com/airportcodes.html:

BER Berlin
CHI Chicago
MIL Milan
MOW Moscow
RIO Rio de Janeiro
ROM Rome
QLA Los Angeles
QSF San Francisco
SAO Sao Paolo
STO Stockholm
TYO Tokyo
WAS Washington DC
YMQ Montreal
YTO Toronto

These should work in all travel search engines, but it doesn't surprise this traveler to learn that these codes might not be properly programmed.