I stumbled across Meebo on another blog, and thought the idea was a good one.  Essentially, you embed a little piece of HTML (actually, a flash object) in a web page, and visitors to your web site can chat live with you through it's interface.  All you need is a Jabber client on your machine. 

It works as advertised, and it's free.  The downside (and the reason I gave up trying to use it) is that every time someone visits your page, you get a pop-up window asking if you want to add the person to your contact list.  Even on this blog, where I get low traffic, it's incredibly annoying. 

According to the developers, this pop-up issue is part of the Jabber standard and won't be messed with.  Too bad, I liked the overall idea.