There are several free, and quite powerful diagramming solutions available as online tools. The following solutions can be used to help diagram software development steps, processes, sitemaps and more. Online applications such as these, make it much easier for people to collaborate when compared with offline software such as Microsoft Visio or OpenOffice Draw. The cost and limited licensing of Microsoft’s product can be a deterrent right from the start. The applications below will address your need to create visually-appealing, easy-to-understand, and cost effective wireframes, flowcharts, sitemaps, and other types of organization charts.
1. Lovely Charts
Google docs added this feature recently
http://googledocs.blogspot.com/2009/09/new-flowchart-shapes-and-multi-line.html
Thank You! I choose “Creately”.
There is also one more free chart building service – My.Origramy, which is based on Origramy flash component for sites.
Nice list! Quickly tried out a couple and went with LucidChart. It looks a lot different now that it’s out of beta and great feature set.