Mail.app implemented on the web using ukijs 
Disclaimer: I'm one of the co-founders of NOLOH (http://www.noloh.com).I want to apologize in advance for being so brash. I find that these demonstrations are very misleading. We all ohh and ahh, but not because of the technical accomplishment, but because of the beauty of Mac interfaces. First, sure the app is fast, it's loading the entire application from JavaScript, yet another fat client app.Second, the capabilities that this provides seems no different than the basics of YUI, or other JavaScript widget collections with unified syntax.Third, it's misleading to suggest that this is Mac Mail when in fact I can't search. I guess that's not a part of the Mail.app.Fourth, 15 hours to do a main screen and a new message form, really?  I'm sure that we or the guys at Cappuccino & Sproutcore could throw a similarly functioning demo together quicker.The hard part of this example is getting the image resources, not the implementation. This implementation could've been done just as well in straight JavaScript or any other JavaScript framework just as nicely.