While I'm still having a bit of difficulty figuring out whether the 30Boxes calendaring service is worth spending any time with or not, I'm having no such difficulty in seeing the value of a service like coComment.
The concept of this is brilliantly simple - provide a means through which any comment you make on any blog (anyone's blog, including your own) are aggregated in a single place so that you can clearly see all those comments from different places and thus get the broad picture of all the online conversations you are taking part in, anywhere. Read more about how it works here.
Not only that, you can then add a bit of code to your own site which displays your latest comments, wherever you make them. I'm trying that out which you can see in the right-hand column.
It gets even better as you can also share your aggregated place on the coComment website so anyone else can also see what you say and where you say it. A sort of shared personal place for all your conversations. A great way to stimulate more conversation with and by others. Take a look - here's my place.
And more! You - and anyone else - can also subscribe to an RSS feed of your comment place so you can get all the comments you've made to a particular post. That RSS feed will also deliver anyone else's comments to a particular post you've commented on.
Now that's a conversation. It makes redundant anyone's notion of where you comment is an important thing. It's not. Who cares where the conversations take place when you can track them, wherever they happen?
coComment is in beta (of course) and you need an invitation to participate. If my experience is any indicator, just go to the home page, fill in the details there and you may get an email invite from coComments directly. That's what I did a few days ago.
This is a terrific service. It works on the major blogging platforms. Still in development, as I said, and the developers have lots of ideas for it. One I'm hoping to see soon - a fully-automated way to capture your comments into coComment. I've got the coComment capture bookmarklet in Firefox, but I keep forgetting to click it when I leave a comment anywhere...