I love lots of heavy Ajax stuff as much as the next guy, but this is crazy. It's essentially a web-based OS with lots of little sub-prgrams and all kinds of UI cred. It's such a good idea you can almost smell Google's heady musk wafting under the door. Just signed up for a full account—password didn't come yet—but the demo is very compelling. It was created by some nerds at MIT, Stanford, and CalTech so you just know it's going to have Xeyes pretty soon.