Most of the complaints specifically mentioned the one-second flash of Janet Jackson's (search) breast, the FCC said.
Others expressed outrage about the overall spectacle, which included bump-and-grind dancing between Jackson and Justin Timberlake (search) as well as Nelly gesturing toward his crotch during his performance.
One e-mail to the agency said simply, "Please do something about the filth on TV."
Nearly 90 million people watched the Super Bowl, including millions of parents and children who caught the Jackson breast-baring incident.
Calling it a "classless, crass and deplorable stunt," FCC chief Michael Powell (search) this week launched an investigation into whether the show violated decency laws. It could result in a fine of up to $27,500 or -- if the FCC applies the sanction to each CBS station -- in the millions.
Jackson has apologized, saying she was "really sorry" if she offended anyone. A spokeswoman has said that a red lace garment she was wearing under her bustier was supposed to stay put.