How do I create a Block that shows the title of a node in alphabetical order as links to that node?

I suppose this will be pretty easy. I need a PHP block I guess that pulls nodes from taxonomy "agent" and orders them alphabetically. One more wrinkle, the Title is actually the agent's full name, it would be nice if I could sort by his last name. I don't know if there's an easy way to do that in the SQL. I'd like to do it this way instead of having a menu where I manually have to add names and sort them with weight (we all know that's a beating).

Thanks for the help.