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.

GitHub Polls - Polls for GitHub issues and readme

Nifty - Manage projects, work, and communications in one place.

Polls for WhatsApp - Create & share quick polls in your WhatsApp groups

Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.

Twitter Polls - Polls embedded in tweets