I’ve been playing with a website/tool called Gliffy which is sort of a web-based Visio. It’s actually rather cool the interface is rather snappy but thats most likely because it a Flash applet inside your browser.
It’s got all the diagram bits & pieces to do floor plans, computer networks, flowcharts and UML stuff and a ton of other similar diagram’s. You can also collabrate on a diagram which is rather useful if you’ve got a team working on a diagram like perhaps a software development team?
With this and something like Google Docs you need office software on your machine less and less and makes it trully possible to be productive on virtually any computer with a web interface. I do wonder how long it will be till someone like Google buys these guys out?
The only thing I found that was missing from it that I would’ve like is a PDF export, which would be nice for when I want to send a diagram to someone, they do have PNG, SVG & Jpeg.