Recently I’ve found myself doing a lot more work with Microsoft Lync 2010. Microsoft supply some really good guidance on Lync topologies by way of reference architctures, which are available on TechNet.
The diagrams included as part of the reference architectures are very impressive. Have a look here. Happily you can download these architecture diagrams in Visio. When doing a Lync design in Visio the follow are a must have: