I also use Travelocity, TIS, not for booking tickets but for comparison and to find out which airlines fly into a certain airport. I've found that most of these "money-saving" sites quote almost the same prices that you can get from the airline's website itself.

I've never tried kayak.com, but will certainly check it out if recommended. We have found that hotwire definitely gets you some of the best rental car deals around. We were recently in Florida. Everyone was quoting $80-90 per day plus taxes, fees, etc. for a compact car. We got an H3 for $312 for the week, including the tax.