はてなみたいに /user_name/ ってやる routes
map.with_options( :path_prefix => '/:user_name', :requirements => { :user_name => /[a-z][0-9a-z_\-]{2,30}[0-9a-z]/i }, :name_prefix => 'user_', :namespace => 'user/' ) do |user| user.root :controller => 'index' end
こんな感じで。