At our PAX Prime 2012 panel, we got an excellent question that suggested we should consider using reviews to talk about whether or not the game being examined is playable for gamers with disabilities, and to what extent it's playable. Truth be told, it wasn't something we had even thought to consider, which highlights the problem: this is one of those issues that doesn't get discussed enough.
It was great timing, then, to come across the Game Accessibility Guidelines project (via RPS). The website offers basic, intermediate, and advanced guidelines that take into consideration factors such as potential reach, impact, and cost to implement. A surprising number of the suggestions wouldn't be terribly difficult or even expensive to do -- if they were included in the planning stages early on.
While this is intended as a resource for developers, it's still worth reading if you're someone who cares about videogames and is in a position to help spread the word about (which you probably are). Many of the guidelines presented on the site would improve games for everyone, not just those with disabilities.
Gaming For Everyone: Game Accessibility Guidelines [Rock, Paper, Shotgun]