By-the-hour painting commission for ~xXblackwolfXx, done in Photoshop with an Intuos 3! Originally commissioned for 6 hours, but she has been kind to me over the years and a repeat customer, so it's more like 8.5 hours I think.
It's no special brush or trick or anything, painting fur is the same techqnieu as painting anything. Paint dark to light, get your lighting right, paint your big shapes first and work down to your little shapes. So I paint the shape of the figure first, ignoring the texture. Then go in and define large chunks of fur and how it flows, then the details! *Sullivan has some great fur tutorials in her gallery, and if you feel you need it, some brushes that are fur specific. Hope that helps!