My colleague Erno (click for his blog) sent me this link: http://blogs.msdn.com/roberdan/archive/2006/03/05/543967.aspx
A guy called Roberto D'Angelo created a visio template you can use if you want to design a Sharepoint portal site layout. Really nice tool if you need to quickly show your customer what your portal solution is going to look like.
I just received an e-mail from Ferry den Dopper. It appears not Roberto but Ferry created the visio template and Roberto was only referring to it.
My apologies go to Ferry, visit the links below to download the templates at his new blog (updated links oct'08!):