Gliffy.com

MS Visio simplified - create plans and drawings on-line

Add your comments or examples of something you've done here.

Here's an example of a gliffy image in a web page. And the gliffy stored imageshows the original.

This seemed an excellent alternative to Visio. However it is a 'subscription' service if you want to create something for yourself or to share privately with colleagues. If I were planning a network using this, I might not want to share it with the world