CreatelyNovember 24th, 2009
Creately is an online diagramming tool which makes it almost feel like a web version of Visio. This flash based tool definitely has nice collaborative support that allows sharing and commenting. On top of the expected flows, workflows, sitemaps and UML diagrams, if one looks closely under the hood, Creately also allows to mockup quick UI representations. The User Interface Mockups tab of course is loaded with a bunch of preexisting interface patterns ready to be dragged and dropped.
Try it out yourself and sign up here.