Business Week has an article about the latest research that shows that sitting in a chair (any chair) for hours each day is harmful to your health.
Excerpts from Business Week’s "Your Office Chair is Killing You":
Hamilton, like many sitting researchers, doesn’t own an office chair… The data back him up. Older people who move around have half the mortality rate of their peers… The best sitting alternative is perching—a half-standing position at barstool height that keeps weight on the legs and leaves the S-curve intact. Chair alternatives include the Swopper, a hybrid stool seat and the funky, high HAG Capisco chair. Standing desks and chaise lounges are good options. Ball chairs, which bounce your spine into a C-shape, are not.