The RIAA is more of a political organization than anything else. It is comprised of 5 or different music companies, which in turn give money to the RIAA, who then lobbies politicians, et.al. Universal, WEA, BMI, etc.. as individual companies do not have a lot of clout, but as a group it is a whole different story..
I am also going to post the following link in the Cool Web Sites area… Boycott-RIAA. It seems to have some good info on what the RIAA is and what it does.