Here are a few of my Visio drawings. I will be adding to this collection as I have time. I left this page open for comments so if you see anything you like or think sucks, let me know!
48-port 3750 Catalyst Template
24-port 3750 Catalyst Template
Logical overview of mail flow in Exchange 2010
Logical outside mailflow in Exchange 2010
Load balanced edge server logical overview for Exchange 2010