One of my current Guardfiles

Guardfile

# More info at https://github.com/guard/guard#readme

guard 'ego' do
  watch('Guardfile')
end

guard 'spork' do
  watch('config/application.rb')
  watch('config/environment.rb')
  watch(%r{^config/environments/.*\.rb$})
  watch(%r{^config/initializers/.*\.rb$})
  watch('spec/spec_helper.rb')
end

guard 'bundler' do
  watch('Gemfile')
end

guard 'rspec', :cli => "-r rspec/instafail -f RSpec::Instafail --color --drb" do
  watch(%r{^spec/.+_spec\.rb})
  watch(%r{^lib/(.+)\.rb})     { |m| "spec/lib/#{m[1]}_spec.rb" }
  watch('spec/spec_helper.rb') { "spec" }

  # Rails example
  watch('spec/spec_helper.rb')                       { "spec" }
  watch('config/routes.rb')                          { "spec/routing" }
  watch('app/controllers/application_controller.rb') { "spec/controllers" }
  watch(%r{^spec/.+_spec\.rb})
  watch(%r{^app/(.+)\.rb})                           { |m| "spec/#{m[1]}_spec.rb" }
  watch(%r{^lib/(.+)\.rb})                           { |m| "spec/lib/#{m[1]}_spec.rb" }
  watch(%r{^app/controllers/(.+)_(controller)\.rb})  { |m| ["spec/routing/#{m[1]}_routing_spec.rb", "spec/#{m[2]}s/#{m[1]}_#{m[2]}_spec.rb", "spec/acceptance/#{m[1]}_spec.rb"] }
end

guard 'cucumber', :drb => true, :profile => "spork" do
  watch(%r{features/.+\.feature})         { 'features' }
  watch(%r{features/support/.+})          { 'features' }
  watch(%r{features/step_definitions/.+}) { 'features' }
end

guard 'livereload' do
  watch(%r{app/.+\.(erb|haml)})
  watch(%r{app/stylesheets/.+\.(sass|scss)})
  watch(%r{app/helpers/.+\.rb})
  watch(%r{public/.+\.(css|js|html)})
  watch(%r{config/locales/.+\.yml})
end