Oh, and you can do an AO pass. The Render menu lets you do separate passes, or there is a script that allows you to select just one pass for your render... I'm not home now so I don't remember what it is, though.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)