Is it possible to add an at the end of a created with the collection_select helper method?
Right
Agreed on the short answer No and long answer " Be Crafty ", but here's what I just did which I think is simpler than either of these two solutions and worked for me:
Wrap the next line inside erb tags i.e. <%= and %>:
f.collection_select :advertisement_group_id, AdvertisementGroup.find(:all, :order => "name DESC") << AdvertisementGroup.new(:name => "New Group"), :id, :name, :include_blank => true
Just create a new object with .new and pass in whatever text you want displayed along with :include_blank => true.