I just came across an excellent discussion on simplicity in software (via a post on scary software). It's on the blog of Nick Bradbury, who wrote Homesite and FeedDemon:
It's of special interest to me right now as I develop an application that users actually have to... you know, use. I picked up a few ideas here, like this:
"Sometimes in beta versions I'll deliberately remove (or obscure) access to a specific feature just to find out if people really use it. If a lot of beta testers complain about the feature being removed, then it's an 80% feature that needs to be an obvious toolbutton. If only a few complain, then it's a feature that only 20% want so it can be demoted to a menu item."