We freightquote.com
They are pretty cool to work with. Basically they compare a bunch of different freight company rates for you. Make sure you figure out what class your goods are, and make them standard size pallets, that way they dont hit you with a surcharge.
We also use a company called dot-line transportation. There rates pretty reasonable. Call them up and see what discount they can give you on the regular rates. Tell them your going to be shipping out a lot of merchandise and they will set you at a high discount. Once they put your rate into the computer, they usually dont check to make sure you meet the minimum requirments for that discount rate.
Lasty, you can contact UPS. They have a new LTL(less then truckload) service. From what ive heard, they have to good rates as well.