Visio is always an great product that allows you on Creating visual representations of your Microsoft Office and Office 365 architectures, including Microsoft Exchange, SharePoint, and Lync which is a helpful way to communicate your deployment.
I would say, the most beautiful product in the range. and now with 2013 version you can get more specific icons sets for specific diagraming. you can download these custom stencils which each has over 300 icons.
Exchange 2013, Lync Server 2013, and Microsoft SharePoint Server 2013 – Download
Microsoft Exchange 2013 deployments, including on-premises, hybrid, and Office 365 – Download