Actually, I really prefer fully threaded boards
myself. :P  My favorite formats are the UBB fora
(Ultimate Bulletin Board from Infopop, like 
hardwarecentral's) and DCboards like that used at 
Collector Heaven (which, actually, is also 
available as freeware). Fully hierarchical with 
new posts/threads staying on top, required login 
... ^^ The linear models get confusing quickly if 
you have more than a dozen people posting ..