Let's say you just rented a car through your favorite travel site.
Try this: Forward your confirmation message—the one with your reservation details—to firstname.lastname@example.org.
The freebie:New siteAutoslash will track prices for your dates and pick-up location. If prices drop because of a last-minute sale, you'll be e-mailed. You can then go back to your favorite travel site, cancel your reservation, and rebook at the new, lower rate.
Only works for domestic rentals.* Autoslash will collect your e-mail address and may use it for future promotional messages to lure you into renting cars through its own, Travelocity-powered service.
The verdict: Longtime travel blogger Gary Leff at A View From the Wing says this new service is especially useful and not a gimmick. I agree. But it's new. It has glitches. If you try it, please share your opinions in the comments. Thanks.
*Corrected at 10:23 ET. Sorry.