The Controller Project from Caleb Kraft of Hack-a-day is an excellent new addition to the gamut of people sharing and promoting game accessibility solutions.
I've long been an advocate of people finding their own solutions, but for some people the range of possibilities and barriers they face are utterly daunting. For that, thank goodness for the likes of the charity SpecialEffect (at least in the UK) and their loan-library, games-room, OTs and home visits. Anyway, here's some more D.I.Y. resources for accessible gaming tinkerers:
Acid-Mods: A forum full of ideas for hacks and solutions. It's dried up a bit recently but still worth trawling through.
Hack Ability Blog: A more "life-in-general" hacking blog with top ideas.
Dual-Ring: A brilliant game accessibility site, that shares some very affordable/free hacks/get-arounds for improving access such from Auto Hot Key scripts to adapting Ikea furniture. A must see.
Makey-Makey Hackcess: The brilliant and very easy D.I.Y. controller that works on PCs out of the box, and using the Cronus Device and Bullseye software, can be used on Xbox 360 and PS3. Huge possibilities, especially if you link it other controls with JoyToKey. More on that soon.
One Switch D.I.Y. pages: also try searching this blog on "hacked", "adapted" or "enabled". Loads more links here to easy to complex adaptations from me, and the likes of Gavin Philips and Ben Heck.
Sugru: Wonderful blu-tack feeling material that sets hard for easy physical adaptations. More to follow on that soon.
And there's tons more besides this. If you have any that I've not mentioned though, do feel free to get in touch to share them. Happy hacking.