This caution is usually justified, particularly when it comes to credit reports. Some companies use the offer of a "free" credit report or score to sell expensive credit-monitoring or other subscription services. The best-known example: FreeCreditReport.com, the subject of entertaining commercials featuring scruffy losers with bad credit. Since 2005, Experian, which owns FreeCreditReport.com, has paid the Federal Trade Commission $1.25 million to settle charges that its ads were misleading.

In recent months, though, several companies have launched websites that provide a credit profile at no cost.

The score you'll get from these sites is not the widely used FICO score that lenders use when you apply for a mortgage, credit card or car loan. But if you're simply looking to improve your credit standing in 2010, these sites provide a useful snapshot of where you stand.

None of the websites mentioned here require you to enter a credit card number, which means you don't have to worry about finding surprise charges on your credit card bill. They rely on advertising for revenue, so be prepared to see a lot of ads for credit cards, mortgages and other products.

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Here's what we found in our test drive of the free sites:

•Credit Karma (creditkarma.com). This site offers a score based on information provided by TrueCredit, a division of TransUnion. This is not the same as a FICO score, but Credit Karma will give you an idea of whether lenders consider you an excellent, average or poor risk. You'll also get a report card grading different components of your score, such as your payment history.

You can update your score as often as you want. If you're working to raise your score, this will help you gauge your progress. Credit Karma CEO Ken Lin recommends checking for updates once a month.

Another helpful feature on this site is the "credit simulator," which shows how various financial transactions would affect your credit. This is a useful tool if you're planning to apply for a mortgage and don't want to do anything that would hurt your score.

•Quizzle (quizzle.com). Quizzle's score is based on information from Experian, and when you sign up, you'll also get a copy of your Experian credit report. Quizzle subscribers are eligible for an updated Experian credit report and Quizzle score every six months. More frequent updates cost $7.

Quizzle gives you grades in several categories, such as your mortgage, budget and rainy day fund. You'll receive an analysis of each category, along with suggestions on how to raise your grade. You'll also receive an overall score based on a scale of 1-100.

Unlike the other free sites we tested, you don't have to type in your Social Security number. Quizzle uses information you provide and asks targeted questions to locate your credit report, says Todd Albery, CEO of Quizzle.

However, if the information you provide delivers more than one credit-report match — which might happen if you have a common name — you may be asked to provide a Social Security number, Albery says.

Along with your credit report, you'll get an analysis of your home value and your mortgage. Quizzle is a subsidiary of Rock Holdings, which also owns mortgage lender Quicken Loans.

•Credit.com. This site's Credit Report Card tells you whether your score is bad, poor, fair, good or excellent, and how that translates into an actual credit score. For example, an "excellent" rating would mean a FICO score of 750-850. You'll also get a grade for components of your credit score. You can update your credit report card every 30 days. Credit.com uses information from TransUnion.

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This site does a good job of breaking down the information used to develop each of your grades. For example, under "payment history," you'll get a rundown of how many late payments appear on your credit report.

While credit scores and snapshots are useful tools, you should periodically review your actual credit reports for errors that could hurt your score.

You can get all three of your credit reports at no cost at AnnualCreditReport.com. The credit bureaus are required by law to provide you with a free credit report every 12 months through this website.

Sandra Block covers personal finance for USA TODAY. Her Your Money column appears Tuesdays. Click herefor an index of Your Money columns. E-mail her at: sblock@usatoday.com. Follow on Twitter:www.twitter.com/sandyblock