I'm just claiming my blog on Technorati,
If you're wondering why you should take the time to claim your blog on Technorati, it's quite simple, you'll get extra visitors to your site,which is always a good thing, and they're likely to be pretty targeted visitors, people looking for exactly what you're blog is about, so the best kind of visitors you can get!
It only takes a few minutes to do and you can add the Technorati widget to your sidebar which adds a whole bunch of extra keyword based tags to your blog.
There's also the "social proof" aspect, as the widget can display your Technorati "Rank" and the higher it gets the more likley people are to see you as an expert in your field.
If you haven't claimed yours yet, check out the video I made on BlogTactics to see how:
the video's not very long and it shows you how to go through the whole process, including how to add the widget to your sidebar, so go get it done already!