Gliffy is a free, easy to use graphical creator/editor, ideal for generating diagrams, flow charts, etc. It provides a set of simple shapes and icons that can be dragged to the campus, edited for size, shape, and color, and can be connected by lines and arrows. You can invite others by email to co-edit the same document. When it is all done, you can export it as a graphic or you can use built-in tools that provide the steps to publish it on a weblog site.
I just sat down and created the following graphic based on my decision on needing to make diagrams, not having money for an artists, and lacking the skills to draw in software...
Some other Gliffy diagrams I have created:
* Streaming Audio into Second Life
* Conceptual Changes for NMC Web site
And see what others have done:
* David Warlick's Blogging / Literacy diagram
* Solution Watch's gliffy examples
* David Lee King does a quick example
See more gliffy examples or watch the screencast on gliffy's Create Great Looking Drawings in a Snap.
Did I mention it was free?