Car or a house purchase
Consumers planning a major purchase might as well get a free trip thrown in.
If you're in the market for a new car, check out DealerMiles.com, a car dealership voucher program that offers miles with nine major airlines.
If you're about to buy a house, check out mortgage lenders that offer partnerships with airlines to see if you can rack up miles in the deal. For example, LendingTree says on its Web site that it offers 1,250 miles on several major U.S. airlines per $10,000 financed.
Meanwhile, Miles4RealEstate.com says it offers 10,000 airline miles per $100,000 of real estate transaction value for brokerage, mortgage and title insurance, moving and relocation, and other home services.
Some home or car insurance companies offer miles to people who request a free rate quote.
For example, a quote on auto, home or renters insurance policies at Liberty Mutual Insurance will earn you 500 American Airlines or Delta Air Lines miles. An auto quote at Sentry Insurance nets 1,500 Delta miles.
At 21st Century Insurance, you'll get 300 Delta Air Lines miles and 200 US Airways miles for an auto insurance quote. If you actually purchase a policy with 21st Century Insurance, you get an additional 2,000 miles on US Airways.
Netflix customers can earn miles on a variety of airlines for signing up for its $8.99 per month subscription plan. Miles range from 1,500 on American Airlines to 3,000 miles on Delta Air Lines.
In Canada, earn 350 American Airlines miles when you sign up for free trial movie rentals at Zip.ca.
United Airlines, through its United Mileage Plus program, offers frequent-flier miles for subscriptions to more than 50 newspapers, including The Wall Street Journal, The Washington Post and Newsday.
Some newspapers also have partnerships with other airlines; for example, a 26-week subscription to The Wall Street Journal nets 1,000 Delta SkyMiles.
Surveys and marketing questionnaires
If you have some time on your hands, earn points by signing up with marketing companies that offer free miles in exchange for your honest opinion.
Companies that offer such programs include e-Miles.com (which can earn you points on several major U.S. and international airlines) and e-Rewards.com.
Several national tax preparation companies -- including H&R Block and TurboTax -- offer miles for preparing your taxes. Make sure you ask about how many frequent-flier miles you'll get -- and the airlines they are affiliated with -- before you sign up.
Bottom line: Check the fine print
Remember, a free ticket may mean inconvenient travel times or days.
"It is easy to earn miles, the problem is on the redemption side," says Winship.
For example, there are capacity controls on every airline, meaning that there will be limited seats available when redeeming frequent-flier miles.
"This does detract from the value of (frequent-flier programs)," says Winship.
Also be aware that frequent-flier programs have recently come under government scrutiny for failing to honor miles. In November, Sen. Charles Shumer, D-N.Y., called for the Department of Transportation to look into complaints from frequent-flier program members regarding expired miles.
Finally, Steiger warns that deals come and go quickly. Grab them while they are available and keep your eyes peeled for new deals.