www.pjirc.com PJIRC is the best Javachat I know of, even better than jpilot. Best part, it is 100% free. Not only free in the sense of not paying, also free in the sense of you get the source code, so you can make any changes you see fit. The only downside is, since it is free, it means it is not signed with a trusted certificate (since that would cost the author a lot of money) and that means security warnings might popup in people's browsers. But I don't know of any free applets that do not suffer from that problem.
