Google Finance
So if you havent, please check out http://finance.google.com/. There is a lot of flash and AJAX running this service. Note how when you add/remove items from your portfolion, the page doesn’t reload completely, just the data sections that display your data. This is how traditional apps work, however, without AJAX, this would be near impossible to achieve. Great job again Google on leveraging the buzz and buzzing the leverage.
In a side note, Bill Gates taunts Google.