PBS
Pbs: People and Discoveries: Kdka Begins to Broadcast 1920
This site from PBS details the history of radio and KDKA (Pittsburgh, Pennsylvania) the first radio station to offer programming. Mentions: advertising, NBC Radio, mass culture.
Other
History tv.net
This site has an archive of original photographs of important events and broadcasts in the early history of experimental television. Concentrates on the archive of photographs from Vladimir Kosma Zworykin.
Independence Hall Association
U.s. History: Radio Fever
Radio created a mass entertainment culture that could bridge the gap between those in California and those in New York. Read about the advent of radio stations, and the companies that owned them. See why the federal government had to...
My Hero Project
My Hero: Philo T. Farnsworth
"One of the more important inventors of the twentieth century," Philo T. Farnsworth invented the television. Use this site to learn about how he was inspired to create the television and why Farnsworth isn't always credited for his idea.