Co-Ment is a Web service for annotating, discussing, and writing texts online. The editing environment is wiki-like, supporting many syntaxes (Markdown, RST, and HTML), and allows for finely controlled layouts including tables and images. Users can comment on extracts of the text, and advanced comment navigation features allow new annotations to be discovered or the history of a debate to be browsed. It is also possible to set up an email alert for text edits or new comments. Import/export is supported for many formats including TXT, DOC, ODT, and HTML.