The link below contains an OmniGraffle Stencil (OmniGraffle is like Visio for the Mac) for the integration patterns described in Enterprise Integration Patterns. The stencil contains notation based on the authors' descriptions of the patterns. The book is one of the best resources available on messaging systems.

The Stencil, like the book, has Message Endpoints, Message Construction, Message Routing, Message Transformation, Messaging Channels, and Systems Management patterns included.

Download OmniGraffle Stencil (zipped)

Note: if you are a Windows/Visio user, the Stencil is available from the author's site.