Jiglu is a new tagging service launching in open beta today. Its goal is to take the work of tagging posts out of the hands of bloggers by automating the process entirely. All you need to do as a blog owner is install the plug-in, which supports itself by showing small, unobtrusive AdSense ads inside the lightbox where you search and browse blog tags.
The service works by spidering your pages and pulling out keywords where it sees fit, and listing them in a number of ways. My personal favorite is the TagMap, which takes your tags and organizes them by shape and color (as seen at the bottom of this post). The larger tags are the ones that get used more often, while the smaller have less frequency.
Prior to launching on the consumer front the service had enterprise roots, and was formerly known as MailSpaces. It since moved on to targeting bloggers with the tagging solution, and have an enterprise-centric white label version in the works that will let companies auto-tag and sort through their content without ads.
While I think there's still a great deal of merit for site search, something Google still handles very well, searching and sorting content by tags in the same space a more exploratory experience, and something that's bound to get users to find new content they might not otherwise have stumbled upon themselves. It's also a whole lot easier than categorizing or tagging each of your posts by hand.