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.

Tasker - Tasker is an application for Android which performs Tasks (sets of Actions) based on Contexts...

Planyway - Visual project management for Jira and Trello: manage resources, build project roadmaps, use time tracking.

Automate - Automate various tasks on your Android smartphone or tablet.

Corrello - Dashboards for agile teams using Trello

Locale - Locale helps content owners and translators work together, so Rails developers are free to write more code