1. SkyLow.com is a new venture which aggregates into a search engine quite a large number of worldwide low cost airlines. Their advantage is that they allow bookings on their site rather than redirect you to the airline. The ability to make a booking is great as in 4 steps they make a booking. They are growing every week with more and more airlines. They have an amazing tool to find cheapest options: Deal Finder. Skylow.com seems to target the backpackers and low budget travelers as they are regional flights focused.

2. Want a vacation to Hawaii? Go to Airtohawaii.com and get a free night package!

3. If you make a reservation for your flight to fly during the week you can often be able to get a further discount on an airfare to Las Vegas. Furthermore, because Saturday is one of the busiest days for most carriers on which they often levy premium rates, many of the carriers offer discounts on airfares to travelers whose trip includes a Saturday night.
4. Sign up for newsletters that will email you when exceptional airfare savings are available

5. Airfare prices tend to be better between 14 and 21 days before your target date. Airlines try to entice you to buy 2 or 3 weeks in advance with price breaks on airfares. This way the flight fills up and they can increase the profitability on that route.

6. If an airline is facing the possibility of breaking even or losing money on a particular route, they will frequently slash airfares the day before departure to entice travelers to book those airfares.

The downside is that this is a crap shoot. If you wait until the last minute to buy, you're at the mercy of chance and could possibly end up having to pay premium airfares because the flight is nearly sold out.

A self-taught expert's guide on how to get free everything on a trip: http://cheapesttravelever.info