Popular stencils
Protocol/Data Block Design
This is a 32-bit ruler and a data field for laying out protocol specification diagrams like commonly used in RFCs and similar publications.
Object Role Model
A stencil for drawing ORM schema's using the new ORM2 Syntax.
Microsoft Azure
This is a Stencil for Microsoft Azure Cloud Platform based on icons shared by on David Pallmann. Hope this helps someone. http://davidpallmann.blogspot.ca/2011/09/windows-azure-design-pattern-icons.html
Windows 8: Category views
Category views for Windows 8.
Constellation 2
A collection of astrological signs. (Part 2)
Cisco CVD 2014 Collaboration Icons
Cisco released updated CVD Icons in many formats, but of course, no Omnigraffle stencil. These are built from the PNGs. http://www.cisco.com/c/en/us/solutions/enterprise/design-zone-smart-business-architecture/cvd.html This is the Collaboration Icons section.
A10 Networks
Stencil for A10 Networks Thunder Series Platforms.
TYPO3 FCE Forms
Elements for designing a FCE Forms for the TYPO3 BackEnd
Workflow nets / YAWL
Workflow nets and YAWL are widely used in academia to teach and discuss the theoretical foundations of workflow and business process management. More information can be found at the official website: http://www.yawl-system.com.