Charitable Americans eager to help the nation of Haiti recover from Tuesday's devastating earthquake are being warned to be on the lookout for online scammers.

A number of "text to donate" services have been set up for people to make donations directly from their cell phones. But consumer advocates are warning that, as more are created, some may be phonies.

Two that are trustworthy are:

-- Texting HAITI to 90999: The U.S. Department of State's Web site suggests texting "HAITI" to "90999" to donate $10 to the Red Cross to help with relief efforts. The $10 will be charged to your cell phone bill. Or you can go online to organizations like the Red Cross and Mercy Corps to contribute to the disaster relief efforts.

-- Texting YELE to 501501: On Twitter, musician Wyclef Jean, a native of Haiti, notes, "Haiti needs your help text YELE to 501501 and 5 dollars will go toward earthquake relief." Yele Haiti is a grassroots movement Jean has set up to inspire change in Haiti through programs in education, sports, the arts and environment.

A published report on The Smoking Gun accuses Wyclef Jean's charity of mismanaging funds, claiming that the group paid him for appearances and has only recently started paying taxes. Jean tearfully acknowledge some "mistakes," but defended his charity publicly, starting "Did I ever use Yele money for personal benefit? Absolutely not."

Andccording to the Internet Storm Center, both of these "text to" options are legitimate services: "Both short codes in use right now, 501501 and 90999, are tracing back to registered twitter accounts and I consider them authentic at this point," says the Center's Johannes B. Ullrich -- however, some charity watchdogs have raised doubts about the ability of Jean's foundation to respond quickly to such an immediate and massive crisis, as well as about some of the foundation's accounting practices.

Other text-to-donate services may arise, and not all of them will be trustworthy.

"Reports of Haitian 'text to donate' scams rising. Only give to orgs you recognize, have researched yourself or are referred by trusted source," noted All Headline News in a post to Twitter.

The Better Business Bureau has already posted advice on its site for those hoping to donate to a legitimate charity. Art Taylor, president and CEO of the BBB's Wise Giving Alliance, agrees that scammers tend to spring up in the wake of catastrophe.

"Whenever there is a major natural disaster, be it home or abroad, there are two things you can count on. The first is the generosity of Americans to donate time and money to help victims, and the second is the appearance of poorly run and in some cases fraudulent charities," Taylor warns.

The BBB points to the scams that appeared in the wake of Hurricane Katrina, which wreaked havoc on New Orleans in 2005. Millions in relief aid were made available to victims; scammers quickly devised "advance loan scams," which required individuals to pay some "fees" up front, say, to process the loan. The promised loans never materialized.

The Federal Trade Commission has warned in the past about unscrupulous calls for donations in the wake of a disaster. The consumer protection agency notes that spammers send e-mails claiming to provide aid to victims and directing you to legitimate-looking Web sites that reference well-known charities or have names that sound similar to well-known, legitimate, and respected charitable organizations. But the spammers keep most -- or all -- of the funds they collect for themselves.

"Not only do Americans need to be concerned about avoiding fraud, they also need to make sure their money goes to competent relief organizations that are equipped and experienced to handle the unique challenges of providing assistance," the BBB's Taylor said.

Meanwhile, the Internet Storm Center reports that some people are already registering domain names related to the Haitian earthquake, the first step toward setting up a Web site. But this doesn't necessarily indicate a scam; such an action could be legitimate, or it could simply be an attempt to "park" the domain name so it can be sold later to a legitimate user.

But some of these domains inevitably wind up being malicious in nature, explains the Storm Center's Joel Ester.

"We don't assume that all of them will be, but it does happen, and it's unfortunate that spammers and phishers prey on people attempting to provide relief for those in need -- especially during such a devastating disaster as this."