The Electronic Frontier Foundation (EFF) has launched dearfcc.org, a web site that gives the Internet community at large a simple way to give the FCC a piece of their mind concerning net neutrality (or the Open Internet Order). You may have heard that FCC Chairman Tom Wheeler has put forth a proposal that would allow broadband providers like Comcast and Time Warner Cable to charge content providers for faster access to their customers (commonly referred to as selling them on "faster lanes" for internet traffic).
Wheeler and the FCC have tentatively approved a preliminary change but will not make a final decision on it until after a "public comment" period (see this EFF article on how the FCC process of making rules works).
The site offers a form letter that you can either fill out yourself or use pre-generated text to get your point across. You can get started here. The ECA, the parent company of GamePolitics, runs an initiative called "Gamers for Net Neutrality" that you should also get involved in. You can find out more here.