FreeRice.com is one of the most ingenious websites of 2007. In the best spirit of the Internet, it offers education, entertainment and a way to change the world -- all for free. All you have to do is visit the site and play a vocabulary game. For each definition you guess correctly, the site will donate the cash equivalent of 20 grains of rice to the U.N. World Food Program. The money to buy the rice comes from the advertisers whose banners appear at the bottom of the screen while you're playing, and the food is largely purchased where it's needed.

Twenty grains of rice per word may not sound like much, but the World Food Program says that in the three months since its October launch, the game has generated more than $200,000, enough to feed more than 700,000 people for one day. It also pulled in $45,000 in donations. Invented by John Breen, a computer programmer from Bloomington, Ind., after watching his son study for the SATs, the site now attracts about half a million players a day, including students worldwide.

FreeRice.com is a nonprofit, but for-profit websites that promise to donate money to charity also have proliferated. Most pledge a portion of retail sales prices to charity, a trend known as "embedded giving." Some "click to donate" sites don't even require visitors to make a purchase, but pledge that donations will be made to save baby seals or offset carbon emissions if a visitor merely clicks on the sponsors' links, sends an e-card or downloads a browser that will send advertisers information about his Web-surfing habits. Such pain-free fundraisers could become a huge boon for charities -- if everybody plays on the honor system. But this new online free-for-all is raising increasing questions about accountability.

Some retailers don't say exactly how much of the purchase price will be donated, or don't specify which charity will benefit, or don't notify the charity in whose name the funds are being raised. And it's difficult for all but the largest charities to monitor solicitations by retailers invoking the charity's name as part of their sales pitch -- especially when the fundraisers aren't children collecting change for UNICEF but for-profit ventures operating on the Internet.

Sen. Robert Menendez (D-N.J.) has introduced sensible legislation that would require retailers and marketers that promise donations to charity to disclose exactly how much of the purchase price they pledge to donate and to which charity. That's a good start, but charities cannot prevent their names being taken in vain -- or collect the money promised -- unless they know about the solicitations in the first place. So the legislation also would require retailers to obtain the charities' written permission in advance.

That would also prevent nonprofits from having their names hijacked by retailers or for products with which they don't wish to be associated. And disclosure will go a long way toward making sure that unscrupulous scammers don't destroy donors' trust and thus spoil the great promise of online fundraising for good causes exemplified by FreeRice.com.