Gabbly is a breath of fresh air. For starters, it requires zero setup--just put the address of the target site after gabbly.com/, e.g. gabbly.com/digg.com--making it super-easy to get other people to join your chat (just send them the URL). Gabbly is easy to use and looks good, and it has a variety of docking options to keep it out of your way. Behind the scenes, it works by capturing the target web site in a frame, which has some drawbacks, but apart from that Gabbly is great for informal real-time chat. It even has built-in RSS feeds. For web site owners there's also a Gabbly component that you can embed in any of your pages by simply copying and pasting a bit of code into your pages. At the moment Gabbly is under the heavy load of the Digg effect, but it's definitely worth checking out if you can.