A little example of what I'm working on just now, Prawn::Graph version two and Prawn::BackgroundDocument, a way to offload the generation of complicated PDFs.

prawn_graph_two_with_background_document.rb

require 'prawn'
require 'prawn/graph'
require 'prawn/background_document'
require 'active_record'

Prawn::BackgroundDocument.generate('some_file.pdf', :callback => [ :completed, :failure ]) do |pdf|
  pdf.bar_graph Bees.where('number_spotted > 0').order('number_spotted'), :best_fit
end

def completed
  puts "PDF Generation worked!"
end

def failure
  puts "PDF Generation failed!"
end