Markdoc - Markdoc is a lightweight Markdown-based wiki system.

Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

TiddlyWiki - a non-linear personal web notebook

Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.

Banana Dance Wiki/CMS - Free open source software combining the best of wiki and CMS with community building-features.

Wondershare PDFelement - All-in-one PDF editor