Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Obie.ai - Access knowledge quicker without leaving Slack
Planyway - Visual project management for Jira and Trello: manage resources, build project roadmaps, use time tracking.
Slicki - The Wiki for Slack. Build documentation from conversation.
Corrello - Dashboards for agile teams using Trello