logstash - logstash is a tool for managing events and logs.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
log.io - Real-time log monitoring in your browser
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
Fluentd - Fluentd is a cross platform open source data collection solution originally developed at Treasure Data.
Documize - Enterprise-grade wiki and knowledge management platform