In the past few months I've seen no fewer than four services that let you chat in real time with people visiting the same web site as you. Most of them, I'm sorry to say, suck. Either they have crappy interfaces, require every user to install an extension or other software, or just don't work very well. 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/downloadsquad.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.