Along the lines of other recent web aggregators, Netvibes is a useful Ajax application which allows you to create a ‘next generation’ homepage, complete with email, weather, and feeds from your favourite blogs. While similar in design to Google’s new Personalized Homepage, it has a slick interface which allows for easy viewing and the ability to add content, all without page reloads.
If nothing else, you need to check out the register process. Only 3 fields to register, and pay careful attention to the behaviour of those fields as you type. Very nice!