How do I clone a hard disk excluding some directories? In preparation for Lion, I want to make a bootable clone of my system to an external harddisk. I use TimeMachine, but I want to be sure I have a running backup.

Of course, there is much stuff on my system which doesn't need to be secured. This includes ~/Library/Caches and especially the installation of the developer tools (/Developer). To save space, I don't want to clone these. 

Which tool can I use to do that? I have always cloned my harddisks with Disk Utility, but you obviously can't exclude directories with it.
Both Carbon Copy Cloner and SuperDuper can clone and omit files or directories from the clone.