"HOPE FOR HAITI TELETHON" FRIDAY 7:00 P.M. (MTV. CNN AND MAJOR NETWORKS)

George Clooney and Wyclef Jean have been burning the midnight oil, working furiously to raise funds and secure participants for the "Hope for Haiti Now: A Global Benefit for Earthquake Relief" telethon, presented by MTV Networks on Friday at 8 p.m. ET/PT.

The undertaking is expected to be one of the biggest charitable efforts ever. All proceeds from the telecast will be split among five relief organizations actively operating in Haiti: Oxfam America, Partners in Health, the Red Cross, UNICEF and Wyclef's Yele Haiti foundation.

"Hope for Haiti" is the latest in a line of all-star charity events, following in the footsteps of the September 11 fundraiser "America: A Tribute to Heroes" and "Shelter From the Storm: A Concert for the Gulf Coast," which benefited the survivors of Hurricane Katrina.

"America: A Tribute to Heroes" was especially effective, helping raise more than $150 million. The event — broadcast on all the major networks and cable outlets — was also organized by Clooney and featured an array of performances from Alicia Keys, U2 and Celine Dion, among others. CDs and DVDs of the event also helped secure money for the United Way's September 11 Telethon Fund.

"The Concert for New York City" was another notable benefit held after 9/11. Jay-Z, David Bowie, the Backstreet Boys, Bon Jovi and Destiny's Child were just a few of the performers during the five-hour telecast. The Madison Square Garden-hosted benefit helped raise more than $30 million for the Robin Hood Relief Fund, according to organizers.

Hurricane Katrina also drew a large response from Americans. "Shelter From the Storm: A Concert for the Gulf Coast" garnered headlines after Kanye West's outburst against then-President George W. Bush, but the benefit is best remembered for the money it helped raise for the American Red Cross and the Salvation Army. All in all, the telethon helped secure $30 million for relief, according to CBS News.

All three of the events owe a debt to Live Aid, the legendary concert that helped raise money for aid in Africa. Although Live Aid wasn't in response to a specific tragedy, the concert helped set the template for celebrity response. The event was televised in America and Europe as some of the great musicians of all time chipped in to help, including the Rolling Stones, Queen, the Police, the Four Tops, the Beach Boys and Led Zeppelin, among countless others.

In 2004, celebrities and American donors helped raised money for another international rescue effort when the South Asian Tsunami hit. Once again, George Clooney was at the forefront as he organized the "Tsunami Aid: A Concert of Hope" telethon. Madonna and Christina Aguilera were among the notable participants, while Brad Pitt and Halle Berry were a few of the actors who manned the telephones for donations. The American Red Cross International Response Fund reeled in an estimated $18.3 million as a result, according to various reports.

Head here to learn more about what you can do to help with earthquake-relief efforts in Haiti, and for more information, see Think MTV. Join George Clooney and Wyclef Jean for MTV's "Hope for Haiti" telethon, airing commercial-free Friday, January 22, at 8 p.m. ET.