Thunderclap, a mass-messaging service that gained popularity on Twitter, has set its sights on Facebook. Twitter recently booted Thunderclap from operating on its network, so now its organizers are gearing up to run on Facebook.

The first mass-message has already been sent, as the Human Rights Watch used Thunderclap to spread support through Facebook for female athletes from Saudi Arabia. Their country has banned women from competing in the 2012 London Summer Olympic Games. Thunderclap is one of many parties to use Facebook to promote an Olympics cause.

According to Fast Company, if the Human Rights Watch‘s campaign reaches 500 supporters by June 27, the company will focus its operations on Facebook.

How does Thunderclap send messages so globally? By clicking that you support a cause, Thunderclap posts the message to your Facebook page, provoking your friends to join in. Once they say that they’re in favor, it will spread to their friends and so on. The service operates something akin to an organic version of Twitter’s promoted Tweets feature. Thunderclap has been compared to Kickstarter, a social funding platform for creative projects.

Hashem Bajwa, the CEO of De-De (the studio that created Thunderclap), explained Thunderclap’s goal:

Their ultimate mission is to get more people to share more things. Thunderclap helps fuel that sharing, but with a purpose.

Thunderclap developers say they’re trying to work within Facebook’s regulations, so as not to run afoul of any rules. The program was suspended from Twitter after one day, but it was wildly effective. Rolling Stone writer Matt Taibbi sent the first Thunderclap message through Twitter. It reached roughly 4 million Tweeters.

Readers: Would you be OK with this kind of viral marketing in your news feed, if it was for a worthy cause?

Images courtesy of Thunderclap.