I love to use cheapoair for research. It helps me find the best flight times and airlines. I would love to book a flight with them except that after you've paid all their fees and stuff you can usually buy the tickets for less directly from the airlines. For example a few weeks ago I found out that I needed to buy four RT tickets from IND, MDW or ORD to MSY. I tried several other websites including ATA, Southwest, Airtran, Expedia, etc.. tickets were averaging between $300 and up per person.
I then went to cheapoair and tried several combinations and it came up with a RT airfare of $109. Well thats hard to beat right? But once you added all their stuff onto the price it was nearly $200 pp. So I saw the deal they quoted was through American Airlines, I went directly to american's website and specified the time slot of the flights of the cheapo's quote and it came to $128 RT but after taxes and fees it came to around $150 and change. Using it as a research tool has saved me a ton of legwork. Especially when looking for last minute flights.