The Conversation Tracker: Another in the collection of tools to show threaded conversations, this time at the meta-level, across sites. While very difficult to do in the general wide open system of the Internet, tracking topic spread and threads is far, far simpler in relatively closed systems like Usenet (see Marc Smith's Netscan stuff, of course) and LiveJournal. I'd like to see more tools for handling LiveJournal's sprawling disaster of a conversation space.... Now THAT would really benefit a lot of users who are frustrated, and with good reason. (Difficulty following conversation across LJ's was one of the major issues raised by users in my survey results, which I'll digest and post sometime in the next month.)
The Trend Tool: Their tool for simple graphs of topic spread over time. What can I say, I love graphs, especially time series data. I haven't played with it enough to know what I think of it as a general purpose tool, though.
HP Labs Empidemic Analyser: Yevgeniy Medynskiy of Cornell pointed me to the HP Labs work on meme spread, which seems to be evolving into some cool tools. Their thesis is that viral memes and topic memes spread similarly. I'm going off to play with this thing now.
For all these links: BlogPulse Tools, scroll down for the items in question.