I wrote a tutorial on sharing code between JRuby UDFs in Apache Pig and
Sinatra, and I thought readers of the list might appreciate it. It is
really cool to use JRuby to wrap Java APIs and to be able to share code
between Hadoop and a web app thanks to JRuby 
http://hortonworks.com/blog/pig-as-hadoop-connector-part-two-hbase-jruby-and-sinatra/