AJAX Flow Chart Software

I need some online flow charting software. It needs to be easy - like how [login to view URL] has the little arrows you click. Must have a "web 2.0ish" feel. Users must have to login to use and can save the flow chart for future use. When user logs in, they should be able to see a simple account screen with the list of their created flow charts and a "Make a new chart" link. Users must be able to print the chart as well. Users should also be allowed to slightly customize their chart with different colors, fonts, sizes, etc. Thanks.