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.
Slack Jira Integration - Easily keep issues moving right from Slack
Planyway - Visual project management for Jira and Trello: manage resources, build project roadmaps, use time tracking.
Sortd for Slack - Get Trello-style project boards right in your Slack!
Corrello - Dashboards for agile teams using Trello
Actions from Slack - Turn Slack messages into tickets, issues, tasks, and more.