I just learned a bunch of useful information from this Hairpin thread and I thought I'd share with you.
It might not all be accurate, because hey, these are just people on the internet, but if these tips do save me (or you) a few bucks somehow, it's worth a try.
Some of them sound like conspiracy theories, but honestly the technology for most of these things is out there, they are not impossible. The question is if anyone is actually doing them...
Tips from the thread:
1. Book from a pc instead of a mac for lower fares on Orbitz
2. Clear your cookies and your browser history before checking out fares again so they don't "remember" you and your search and charge you more the next time
3. Buying on a Tuesday or Wednesday or whatever day you have heard doesn't work.
4. It's possible that the more people search for a particular flight, the more the airlines jack up the price, so don't search too many times if you can help it.
5. Airlines might also track you by browser and give you prices based on how rich they think you are (avoid Safari I guess?)
6. Someday in the near future airlines might use your IP address to screw you by zipcode, so if you live in a rich neighborhood you see different prices than people in a poor area.
7. If you buy on Southwest airlines, keep watching to see if prices drop after you purchase, and then cancel your flight and rebook (you get to keep the leftover credits)
8. Book directly with an airline instead of on Orbitz or an aggregator for better treatment/upgrades etc. Usually prices will be the same
9. It might be true that fares online change every 15 minutes, so you maybe should ignore tip #4 and search again? After clearing your history, of course.
10. Mostly fares get more expensive as the flight date approaches so book now and don't hold out hope that it will magically get cheaper (though rarely it will)