I think it depends on your ideas as much as anything else. Web Apps? Operating Systems?

For web apps, I love Drupal. Drupal is a php platform, like Rails is for Ruby. PHP was easy enough for me to be building simple Drupal modules within a year of my first install, with Very little prior experience. So, keep in mind that php is not a huge learning curve and you also have jQuery, Apache, linux, project management, etc out there, fucking up your life, ;D