cairo - rcairo
ruby bindings for the gnome graphics library, including support for generating unicode PDFs
RubyForge: cairo: Project Info
rcairo page on rubyforge
PDF::Reader
an unrelased ruby project for reading PDFs
PDF::Writer versus libharu2 « Emmanuel Oga’s Weblog
RubyForge: Prawn: Project Info
greg brown's possible new PDF::Writer replacement
Prawn: Fast, Nimble PDF Generation For Ruby
node.js
interesting presetation on node.js - a server side, non blocking IO library for javascript