http://www.thebmc.co.uk/Feature.aspx?id=1436
http://storrick.cnc.net/VerticalDevicesPage/VerticalHome.shtml

http://www.youtube.com/watch?v=det6haixgnY
http://en.wikipedia.org/wiki/Belay_device
http://www.rei.com/expertadvice/articles/belay+device.html

Brake bar
    http://www.xmission.com/~tmoyer/testing/Simulation_of_Climbing_and_Rescue_Belays.pdf
    http://www.youtube.com/watch?v=Ksl6Ue2fWWw
    http://www.google.com/search?q=brake+bar+rack&tbm=isch

Maybe the "figure eight with heavy load" configuration would work?
    http://www.youtube.com/watch?v=WMvralRauSE