I've always noticed that BoingBoing doesn't allow comments. (Well, they allow other weblogs to link to them and then comment, which is a pretty slackassed and self-serving workaround if you ask me.) I thought, "hey, there must be a way to create a bookmarklet that will let you combine Haloscan comments with BoingBoing."
I came up with this, a bookmarklet I call "ExoComment" because it lets you comment on a page from outside of the page.
Drag the following link to your toolbar, or right click on it and add it to your favorites. It seems to work with Mozilla, Firefox and Internet Explorer.
Once it's installed, just go to a page, then click on ExoComment in your toolbar. A Haloscan window will pop up and let you post your comment. ExoComments are page-oriented, so if you want to comment on a particular item in a page, you have to open the permalink for that item, then comment on that.
It's a hack, but it seemed to work for all of the pages I tried it on. If Haloscan changes their internals, it'll stop working though. They also might get pissed off and cancel my account. Who knows, give a try anyways... it's rilly kEwL!