Venture capitalist Guy Kawasaki had to endure too many inept PPT presentations so he came up with his 10-20-30 rule: 10 slides in 20 minutes using 30 point fonts.
Link to his blog post: http://blog.guykawasaki.com/2005/12/the_102030_rule.html#axzz0mJYpUUpX
Excellent!