Low fare airlines: JetBlue, AirTran, American Trans Airways, Southwest, Frontier...I'm sure I'm missing a few, but those are some of the popular ones.
Many of these fly to the "off" airports in some cities (i.e. Midway instead of O'Hare, Hobby instead of Bush Intercontinental, Long Beach instead of LAX, Oakland instead of SFO, Newark instead of JFK/LGA, etc.). This can be useful for Chicago/Northwestern, Baylor, UCLA/USC/Irvine, UCSF, and NYU/Columbia/Cornell/Einstein/Sinai/NYMC respectively.
JetBlue's hub is JFK instead of LaGuardia, since LGA landing spots are hard to come by. They fly to Long Beach and Oakland and their prices are great. They are almost always on time, if not early, and part of this has to do with being at JFK, which is much less crowded than LGA.
Also, look for flights on major airlines to off airports, which can sometimes be cheaper.
If you're going to Yale, a flight to Bradley (Hartford/Springfield airport) will probably be cheaper than flying into New Haven via USAirways Express, although New Haven-Tweed airport is only 10 mins from campus, whereas Bradley is at least 50 mins away for most drivers (much longer if you take the CT Limo shuttle).
If you're going to Wake Forest, look at flights to RDU, as it's maybe 45 mins away down I-40, and you could rent a car. Or if you're going to Duke or Carolina, try Greensboro for the reverse route. Charlotte is an option for Wake Forest, but it's quite a bit farther than RDU, and may be more expensive.
If you need to go to LA from somewhere, and the flight to Oakland is much cheaper, you can take a shuttle flight from Oakland to LA (or do the reverse). It's an extra flight, but you can save some dough sometimes. Similarly, on the east coast, you can take the USAirways shuttles between DC, Boston, and NYC. In fact, between NYC and DC as well as NYC and Boston, you can get a GoYouth fare of $98 if you fly off peak (must be 22 or younger).
-RA
