IKEA has a chair that I'm drooling over - it has a slight slope downward. I can't sit in chairs that slope upwards - they're really hard on my back and very difficult to get out of.
I have a few friends who use a saddle chair, especially when they're machine quilting, and they LOVE it. I might have to drool over those, too.
http://s7d3.scene7.com/is/image/Sall...i=225&fmt=jpeg,rgb&qlt=85,1&op_sharpen=1&resMode=bicub&op_usm=0.9,1.0,4,0&iccEmbed=0
http://www.htf.fi/wwwdata/htf/2005/salli1.jpg