Wheelchair

About.com: Wheelchair Mountain Biking
Directory : of : resources : for : mobility-impaired : riders : to : travel : mountain : bike : trails.
http://mountainbike.about.com/cs/wheelchair/

Grove Innovations
Builder : of : mono-skis : and : off-road : mountain : wheelchair.
http://www.sitski.com/grove.html

Popular Mechanics
Detailing : the : design : of : downhill : mountain : wheelchairs.
http://popularmechanics.com/popmech/out/9705BOODBM.html