I have done quite a bit of reading on color over the years, but proportion is something I really don't know much about. Was just watching a pretty cool presentation (Design for the coders mind), where the presenter talked about how he likes to use 3/4 proportion, and basically just starts from a pt size and works his way up when choosing font sizes for websites. I thought that was a great idea, and banged out a quick ruby script to do it for me

# Calculates a collection of points in the same propotion
# defaults to 3/4, as suggested here  
# http://www.slideshare.net/kadavy/design-for-the-coders-mind-reverseengineering-visual-design-presentation

PROPORTION = 0.75

n = ARGV[0] || 10
start = ARGV[1] || 7

pt = start * PROPORTION
n.times do
  pt = (pt / PROPORTION).round
  puts pt
end