http://www.kayak.com/explore Enter your airport and it will show prices to various destinations on the map.
I usually use Skyscanner.com If it's a trip I'm not in a big hurry to buy, I'll add it to my price drop alert list on Tripadvisor.
escapehouston.com is great for stuff coming out of houston, austin, san antonio and occasionally dallas
Seconded. Skyscanner doesn't always give accurate prices but its good at pointing you to the airlines with the cheapest prices. Many times you have to go the airline's site to get true prices. Additionally once you figure out which airlines are cheapest you can try creative things like booking one way with one airline and one way with the other. There are all kinds of weird combos you can do to lower cost. For example, a few weeks ago I flew to New York City on Sun Country Airlines in one direction and Frontier on the way back. That combo turned out cheaper than using either airline for the whole round trip.
I pretty much swear by hipmunk.com. I recently just booked a multi-city round-trip ticket from IAH to Naples, Italy, then from Milan back to IAH for $875.
For searching I like itasoftware's matrix. escapehouston looks like what I am looking for. A lot of the blogs post deals but many are out of NYC or other major cities.
I've used cheapoair.com a few times with no issue but I'd always check the actual airline vs their price before you buy, on rare occasions the prices on cheaper directly through them.
For some reason I've had a lot of luck using bing.com's flight searcher. Just do a search on "flights from (whereever) to (whereever)" and then there will be an option asking for dates. Just enter those and they will give you several options from many different sites. I just looked for flights from Minneapolis to Istanbul and it came up with several options for roundtrips around $1,000.
I've never used it, but https://skiplagged.com/ is an interesting take on finding cheaper flights. Here's how it works... They were in the news a while back because they got sued by one of the airlines for exposing this info but it's been thrown out. It might be something you should check out.
