Bind Log Analyzer is my first gem :)
It analyzes a Bind query log file and stores the logs into a database (using ActiveRecord). See the details and the source code on GitHub and get the gem on RubyGems. Or simply install it with:
gem install bind_log_analyzer
Starting from version 0.2.1 it includes a simple Sinatra webserver to show some reports and (soon) some cool graphs.