There are several sources from which we can draw:

• Existing wiki engines and their markup
• Various "rich text" formats, like StructuredText, ReStructuredText, Markdown, OLPC document format, even languages like HTML, YAML and XML
• Text-based communication, including e-mails, news, IRC, fora, message boards, instant messaging
• Existing text documents, like RFCs, man pages, project documentation, README files, game walktroughs, etc.