Gliffy is an online tool for creating flowcharts, org charts, database schemas, diagrams, site layouts, etc. Gliffy comes very close to providing Microsoft Visio capabilities on the web.
Gliffy has all the ingredients of a good flowcharting software. It has collapsable palettes, dynamic object properties like Visio, Symbols with drop shadows and stencils with basic shapes.
Gliffy is free (during beta), offers online storage with collaboration and runs inside any web browser with Flash plug-in. Here's a screenshot of Gliffy Diagram Editor inside Firefox.
Gliffy requires no software downloads and works across PC and Mac alike. Since Gliffy is web based, collaborating diagrams between multiple users is simple. Gliffy also stores multiple revisions of the same chart making tracking easier. You can even link your flowcharts Gliffy diagrams from your blog or wiki. Gliffy also has plans of introducing a Web API that will let developers access Gliffy from other applications.
Gliffy is good choice for Google if they like to add a flowcharting tool to Google Web Office that competes with Microsoft Visio. (Google recently acquired Writely)
During the beta period, Gliffy is free to use. As the service matures, premium versions will become available, and an advertising supported version is possible as well.
Gliffy - Diagram and draw in your browser
Launch Gliffy | Gliffy Drawing Examples