Here are some free (and really nice) Visio stencils for networks to accompany the videos from KYSBSUG #114:
Hyper-V Virtualization Stencils
http://www.jonathancusson.com/tag/virtualization-stencil 
Unofficial VMware Visio Stencils
(the ‘icons’ one mentioned in the presentation)
http://technodrone.blogspot.com/2013/04/vmware-visio.html 
Visio Cafe
http://www.visiocafe.com 