Though blogpulse seems to be going nowhere, as far as I can see, it is still one of the most fascinating tool out there. What it does is plot word occurrences versus time on the blogosphere. The recall is rather poor compared to Technorati but the time series plot are very nice.
Here’s one comparative plot that a student in my Information Retrieval course (Mahmoud El-Bachir) has submitted:
You can see clearly when Christmas is (NoÃ«l in French) and when the new year is… I think you also have the Chinese New Year too! (Seek the smaller bump).
My only beef is that I do not have access to the raw data: it would be really cool to build applications on top of blogpulse, but I guess it goes against their business model.