I usually find Priiceline (the OTA version, not the blind bids) finds the cheap fares that other OTAs miss. At least for the US flights.

I also have not had any luck using the website. Either the fares it finds or horrible, or they do not actually ticket when I click through. I guess I could try calling MU direct once I find a fare and see how that works.

On another thread (perhaps the MU thread over on the DL board) some suggested Kyack, but I saw worse pricing there than on Priceline.