A Rails 3.1 app + EventMachine daemon that uses the Twitter Streaming API to continuously fetch and save tweets under certain criteria.
Just like any Rails 3.x app:
bundle install
rake db:migrate
rails server
Then, start the daemon:
./lib/daemons/twitter_logger.rb start RAILS_ENV=development
That should be everything. Now head up to localhost:3000, and start adding Twitter search subscriptions!