If you want to see a great flatspin go to http://www.flyingcirkus.com/default.asp?content=home
In 3DU they have a nice video demonstrating a very clean flatspin. Keep in mind they did it inverted because the airframe "preferred" to spin inverted. Not all planes are like that though. For example Bill Hempel's bipe spins very well upright, but I don't think it will do it very well inverted.