Perhaps you’ve played around with subethaedit or moonedit, but wished for more features, a cleaner interface, or better cross platform support. Gobby does a decent job of addressing most of these issues while adding builtin chat and better per-user customization. The major downside is the complexity of getting it running, it’s not trivial, in fact it’s easier to get running on linux than it is on windows or Mac, but they’re working on that aspect of things and Gobby is well worth a look if you’re interested in collaborative text editing.