This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
I'm not sure what you mean by "types" of action. Do you mean subclasses like DispatchAction? I guess that the analogous thing in Struts 2 would be subclasses of ActionSupport, but you have to understand that Struts 2 actions can be Plain Old Java Beans as opposed to Struts 1, which requires an action to extend the Action class.