I just spotted this spreadsheet that Mark Arend has posted.
The Sharepoint 2007 permissions matrix is a great reference of the out of box permissions and how they map to the default groups.
I’ve printed this one in colour and “it’s going straight to the pool room!”
The other great reference is on the sharepoint solutions page. This is a collection of visio diagrams on all sorts of sharepoint topics. Search for the diagram on application security.