Rubyview-rails is a project mainly written in Ruby, it's free.
Render your Rails views using regular Ruby code
Rubyview is a template-less view layer for your Rails apps.
gem install rubyview-rails
Rubyview-Rails provides a Rails 3 template handler allowing you to create
view templates using Rubyview. Any template with a .rubyview will be handled by Rails.
The Rubyview template handler will interpret your template as a regular Ruby method, and render the return value as its output.
"Hello #{@world}!"