6) Priceline.com offers standard online travel agent services. But its Negotiator is uniquely suited to help you haggle for the best bargains on hotels. Select a minimum star class, your dates of stay and preferred neighborhood, and then name your price. You can save up to 60% off published rates, and bids less than $100 a night on luxury lodgings often win — particularly for last-minute bookings.

But here's the catch: Priceline doesn't tell you which hotel you're booking until after you pay, so you won't be sure exactly where you'll end up. Blind booking like this can be particularly risky when you're visiting an unfamiliar area, especially overseas. Note: The site also allows you to Name Your Own Price for flights and car rentals.

Watch out for possibly fake reviews from cronies trying to push up their own hotel's ratings or flame their competitors (the site flags some suspicious postings). Ignore reviews on either extreme and focus on those with midrange ratings — they're more likely to be the most helpful. TripAdvisor doesn't sell rooms or offer any actual deals, but it links you to partner sites, such as Expedia, Travelocity and Hotels.com. Click on the "check rates" button and select the site or sites you'd like to try — a new window with results will open for each partner.

8) To focus on smaller inns or B&Bs, try searching BedandBreakfast.com. It lists extensive details on even the tiniest inns and, after you provide your e-mail address, sends you promotional codes and "hot deals" in your desired location. You can also search for specific amenities, such as a hot tub and fireplace, or find out whether a place is pet-friendly.

10) If you're traveling alone, or with a buddy or two, you can score a great deal staying at a hostel — without necessarily having to join the backpacker and bunk-bed lifestyle you might associate with this budget-lodging option. Many hostels offer more private, hotel-like accommodations these days. Hostelz.com offers nearly 50,000 listings in about 9,000 cities, and includes reviews from professional and real travelers.

11) For a really great deal, try trading places with other travelers. HomeExchange.com provides the largest network of home swappers, with more than 55,000 listings — about 26% in the U.S. and most of the rest spread throughout the major tourist areas of Australia, Britain, Canada, France and Italy. An annual membership costs $119 and gets you as many swaps as you can manage in a year.

12) JetSetter.com is our favorite private-sale site for luxury-hotel deals. In general, these kinds of sites offer invited members exclusive access to deep discounts for a limited time, and they work best if you're flexible about where you want to travel. JetSetter can have 15 to 30 of these "flash sales" available at once – more than similar sites, which usually offer just a handful at a time — and can save you up to 50% off published rates. The sales typically last seven to ten days, or until they sell out.

13) At CruiseCompete.com, more than 300 travel agencies vie to give you the lowest prices for dates, ports and ships you specify, whether you're booking well in advance or at the eleventh hour. You set up a CruiseCompete account, and they send you their best offers without ever seeing your personal information. Plus, the site has live agents available to guide you through the process through a live chat or by phone.

14) Hotwire.com often offers the best published deals on cars by collecting rates from its eight rental car company partners, including Alamo, Enterprise and Hertz.

The site also offers "hot rates" from rental companies that won't be identified until after you've paid. With rental cars, the risk in taking the blind-booking approach is minimal: A minivan is a minivan, no matter which company provides it. (You can also head back to Priceline.com to try bidding for a better bargain on your rental car.)

15) Hotwire does offer some good prepaid rental car deals in certain international cities, but such bargains are AutoEurope.com’s specialty. Auto Europe offers rentals at more than 20,000 locations worldwide. And if you have any problems with the rental-car provider you're hooked up with, Auto Europe will help you resolve them.

16) Check XE.com for reliable, mid-market exchange rates. Along with an easy-to-read grid of conversion rates on the homepage and a host of other tools, this site offers calculators for travel expenses, credit-card charges and, obviously, currency conversions.

17) Trains are often the fastest and cheapest way to travel within and between European countries. Our favorite American Web site for checking timetables and booking tickets on European train lines is RailEurope.com. But you might be able to catch better deals directly from European railways' sites, if you don't get lost in translation.

18) FlightStats.com can help you plan a smooth trip by advising you on the best time of day to fly from a specific airport and which terminals to avoid for connecting flights. You can also view live updates of flight delays, and sign up for free e-mail and phone alerts.

19) At WebFlyer.com, you can see how your miles convert between programs, learn about changes to your frequent-flier program and discover how to maximize the value of your mileage awards when you redeem them for merchandise or services.

20) You never know when an emergency situation will spoil your travel plans. Buying travel insurance from agencies and travel providers, such as cruise lines, is usually a crummy deal because of price markups and restrictions on filing claims. At InsureMyTrip.com, you can compare plans and prices from multiple insurance providers with just one search and narrow your search results by specifying the kind of coverage you need.