Summer flights from Western USA to Guatemala City, Guatemala from only $257 roundtrip with Aeromexico.
EXPIREDPROMO: Alaska Airlines Buy One Get One Free (e.g. New York to Portland, OR for only $112 roundtrip)
Alaska Airlines are running a promotion where you can buy one coach class ticket and get another for just the taxes and fees.
Cheap flights from Fresno, California to Chicago for only $125 roundtrip with American Airlines. Also works in reverse.