I just saw a great Google Techtalks video of Scott Barber from PerfTestPlus talking about UCML, User Community Markup Language. This is a visual way to draw out how people will interact with your website. It ends up looking a lot like a Markov Chain diagram. It would be so sweet to do this for Ruby on Rails, so that this diagram could be automatically generated from your actual running website. With Ruby's excellent reflection and dynamic language support, it might not even be too painful.