Hab.la is a Jabber chat service designed for being embedded in blogs and other sites. On your site, it looks like a little floating palette on the screen. It works, more or less, like Facebook Chat. On my side, it integrates with Adium or iChat. I’m experimenting with it. I currently have it here on wheatblog and also on this test page. You can style it with CSS and such. I haven’t tinkered with that yet.
Of course, for it to work, I have to be at my iMac with a chat client running, though that is fairly common in the evenings (especially evenings when Gina is working). But, feel free to test it out. And, if I get sick of it on wheatblog, I’ll probably leave up the test page for further experimentation.