I was having a look at Google Labs when I came across their Google Extensions for Firefox page. There are the obvious ones listed that most people will already know about, including the Google Toolbar, but the one that caught my attention was the Blogger Web Comments Extension.
Basically what this extension does is allow you to see what people are saying on their blogs about the page you are currently looking at. It does this by querying Google Blog Search, so it’s not limited to only supporting blogs hosted by Google on Blogger accounts. Provided a blog is indexed there, comments from it related to the page you’re currently looking at should show up. You can also post a comment about a page directly to your blog, although this feature only works with Blogger accounts, and you have to be running Firefox 1.5 in order to install the extension (but of course you’ve all upgraded your browser anyway, right?).
I’ve just installed the extension on my copy of Firefox and it produces some interesting results, although I don’t know if I’ll use it very often. It’s a little bit obtrusive at first, but you can always close the comments box it shows and from then on there’s just a little icon near the bottom right of the window, so you’ll barely notice it. For anyone who’s interested in blogging in general, or just receiving some commentary on the pages you’re browsing, the extension is definitely worth the thirty seconds or so required to download and install it.