Making plugins in rails

Question

I'm looking for a good tutorial about making plugins for rails. Something about ActiveRecords extending with good example app. Have you seen one?

Thank you.

UPD: The one on the guides.rubyonrails.org is rather obscure like for me.

Answer 1

http://www.jeffmdean.com/2008/5/30/tutorial-creating-plugins-in-rails it's look good for me.