Documize - Enterprise-grade wiki and knowledge management platform
X Steps Recorder - A clone of Microsoft's Problem Steps Recorder, but for linux.
Boardist - Personal workspace for all the data
Folge - The fastest tool for creating step-by-step guides.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
Snagit - Screen Capture Software for Windows and Mac