Best4c says it's the "best online diagram tool on earth." A pretty lofty claim, considering how many other chart utilities are out there that have similar feature sets (see Gliffy, mxGraph, Ajax13, Floor Planner, etc.) Best4c offers up a simple drag and drop editor, with a four-pane interface that mimics a other desktop drawing apps. You can pick from a fairly large selection of items to drag into your virtual space, including items for floor planning like desks, couches, and houseplants, all the way to flow chart tools to use as a virtual whiteboarding space. There's even an option to upload your own image, although I couldn't get this feature to work.
Rotating and re-sizing objects is a simple and intuitive. There are also controls to bring various elements up and down on the virtual canvas. The entire environment runs in Adobe Flash, and is very responsive--right down to the sliding control panels which expand and contract to open up each set of icons. When you're all done with your work, you can save it to your virtual storage drive. Each time you do this you get also get a simple URL you can give to others for sharing.
So what do you do with a tool like this? I took the time to re-design my office space. It's also helpful for putting flow charts you might have written down in a meeting, onto something that's able to be shared with others. Unfortunately, there's no collaborative workspace--which means you can't work on a chart with someone else at the same time. For collaborative editing however, anyone can take a publicly shared chart and make edits, saving their creation as a new version, while the old remains unchanged.
So is Best4c the "best online diagram tool on earth"? Frankly I haven't tried them all, and despite a few hiccups, I'm giving it a thumbs up. Just one minor suggestion though, the name doesn't really roll off the tongue.