BiddingForTravel.com is the best-established of the sites posting secret bids. They offer help with airfares, car rentals, hotels and vacation packages. There are literally thousands of posts, helpful FAQs, and a section for reporting glitches in the system.
BetterBidding.com is another site with lots indexed bidding histories. It offers Hotwire and Priceline information.
One of the first rules of good salesmanship is to never reveal your lowest price. Those secrets are the basis of Priceline's success since its start in 1998. Swanky hotels don't want you to know they'll take your reservation at $50/night when they usually receive three times that amount.
So why would Priceline tolerate these Web sites that reveal such secrets? One reason might be the loads of exposure they provide.
In a free society, it's doubtful Priceline could prevent the sharing of such information if it wanted to do so. Clearly, it does not. With Priceline even paying commissions to such Web sites, it's clear they are encouraging these efforts.
Priceline continues to grow when many "dot.coms" are struggling or have ceased to exist.
So you can expect these bid-revealing sites to increase alongside Priceline. Use them wisely.
Start by checking the going rate through the sites of major airlines, hotels, car rental firms, etc. (Expedia and Travelocity are helpful for this research).
For hotels, survey a few four-star properties, then move down to some three-stars or even two-stars (nice rooms, no gift shop in the lobby).
Next, go to the bulletin boards to look at successful (and unsuccessful) bids, then act accordingly.
Realize that because someone got a given room/flight/car rental at a certain price last week, you are NOT guaranteed a similar result tomorrow. Economic conditions change with holidays, travel seasons, world events, and other variables.
Be patient. If you have several months with which to work, don't be too quick to bid a high amount or lower the quality rating.
I recently secured a $133 USD/night room for $48. Not bad, right? The folks at BiddingForTravel were not too impressed. They say I could have done even better with more patience. Learn from my "mistake."