Flying to San Diego and LA next week. Rang around the agencies and used the online sites (gohop, ebookers etc) to find the best flights and prices. Then booked the same flights directly on the airlines' own websites and got at least 10-15% discount on the fare quoted on ebookers etc.
Have a look at the Delta airlines website also. None of the travel agents and few of the websites will book with delta because they are in bankruptcy protection and so ther is a risk that the airline will go bust. That said, they have been in the same situation for about 2 years now - American carriers seem to go in and out of it as part of their normal business practices. they have pretty cheap fares.