Tired of manually having to generate PDFs and then open them to check that it's rendering correctly?
Yeah me too!
git clone git@github.com/addywaddy/pdfsync.gitcd pdfsyncnpm install -g gulpnpm installgulp
Now edit the prawn/my_pdf.rb file and the browser will update to show your changes.
I happen to like Prawn for generating PDFs. If that's not your bag, change the render task and watcher to suit your needs.