Its written for fellow ruby/rails newcomers but covers quite a lot of ground. http://nubyonrails.wordpress.com/2007/07/13/david-heinemeier-hanssons-...
Learn Ruby basics as well as the most important classes for sockets programming, and then look at a working chat application . http://www.ibm.com/developerworks/edu/l-dw-linux-rubysocks-i.html?S_TA...
This is a basic example of how to use ferret, acts_as_ferret, and will_paginate to implement search functionality in a Ruby on Rails application. http://railsforum.com/viewtopic.php?id=14757