Live Aid was big. So was "We Are the World." But never before have so many entertainers and TV networks mobilized so quickly for one cause--on one night.

That night is tonight, on nearly every major channel on your dial. America: A Tribute to Heroes, airing from 9-11 p.m. ET/PT, has turned into an unprecedented gathering of networks and stars aiming to raise money for relief and recovery efforts from last week's devastating attacks in New York and Washington, D.C.

After working through what must have been a logistical nightmare, the details went public earlier this week, with Tom Hanks, Tom Cruise, Julia Roberts, Robert De Niro, George Clooney, Jim Carrey, Bon Jovi and Bruce Springsteen, among many others, signing on. But by the end of Thursday, organizers were still announcing more celebrities and performers, including U2, Celine Dion, Enrique Iglesias, Sting and Limp Bizkit.

The telethon also is enlisting a roster of A-listers to man the phones. Halle Berry, Cindy Crawford, John Cusack, Benicio Del Toro, Jack Nicholson, Brad Pitt, Ben Stiller, Adam Sandler and Mark Wahlberg are just some of the stars who will sit in the "Celebrity Phone Bank" and handle caller donations. Estimates say the event could rake in as much as $30 million, with all proceeds from the telethon going to the United Way and the September 11 Fund.

The stars have volunteered their time--with some making their own hefty donations--and they will gather on both coasts, at undisclosed soundstages in Los Angeles and New York. The event is being produced by Joel Gallen, who's best known for his work on the MTV Movie Awards.

RELATED LINKS:
In the Aftermath: Our special coverage of Hollywood's reaction to the tragedy
Ben Stein reflects: E! Online columnist writes of the day the sweetness died
www.TributeToHeroes.org: Find out how you can help at telethon's official Website
"It won't be a big, glitzy show, and it shouldn't be," Gallen tells the Los Angeles Times. "There will be no live audience, no host, no introductions. It's not a celebration. It will be emotional, personal and intimate."

Some stars will recount stories about heroes from last week's tragedies. Others will recite poetry or give their own personal monologues; Mariah Carey will perform her hit song "Hero"; The Dixie Chicks will debut a new song, "I Believe in Love"; and other musicians are expected to do covers of theme-appropriate songs (expect at least one heartfelt version of "God Bless America"). There's also talk that the show will end with a group rendition of "This Land is Your Land."

The Los Angeles Times reports the idea for the telethon actually came together late last week. NBC was planning its own event, and after CBS heard about it, the two networks got together and arranged a conference call with Fox and ABC honchos to collaborate.

The event is being underwritten by CBS, ABC, NBC and Fox. But publicity for the event has been handled by a veteran Warner Bros. publicist, primarily because the major networks did not want to single themselves out or take credit for the telethon. Network publicists were threatened with fines if they unzipped their lips and spilled any details.

This isn't the first time networks have banded together. During World War II, the CBS and NBC radio networks produced a Christmas Eve special in 1942 starring Jack Benny, Tommy Dorsey and Judy Garland and was broadcast throughout the country.

And in 1953, ABC, CBS and NBC aired a Ford Motor Company 50th anniversary show with Ethel Merman, Frank Sinatra and Edward R. Murrow.

E! is just one of more than three dozen broadcast and cable networks, including the WB, UPN, MTV, PBS, Comedy Central, HBO, Telemundo and Univision and 8,000 radio stations airing tonight's telethon (even networks sticking with regular programming, like EPSN and Nickeolodeon, plan to run information on how to give to the benefit). Prior to the telethon, E! News Daily will also present its own special, Hollywood Unites, at 8 p.m. ET/PT.

Meanwhile, organizers have launched a Website, www.tributetoheroes.org, which will provide a Webcast of the event and remain a donation site after the telethon ends. Yahoo! also has launched its own link at tribute.yahoo.com.