Optimum number of choices for menus/navigation
If on a site, a user needs to put their post into a particular category before they submit, how many choices is too many? What would be the maximum cap before it got confusing?
Avoid scrolling. That's the only hard rule... if the user can't see some of the choices they may not know it is possible. This is also important because scrolling a drop down works differently on various platforms, and often works very poorly. The drop down list should never be taller than a single screen if you can avoid it.