The card-based project management tool by Fog Creek Software. This tag is for questions about the Trello Android app.
In one glance, Trello lets you see what's being worked on, who's working on what, and where something is in the process.
Questions about using the Trello Android app are on-topic here. For general usage questions about Trello ask your question at Web Applications.
You can view a Trello board specifically about mobile features (iPad, iPhone, or Android apps) at trello.com/mobile.