Use Cases and Deployment Scope
1. User stories in form of project backlog
2. Acceptance criteria
3. Creating bugs
4. Analysis ticket
5. Maintaining story workflows (from ready for dev to closed)
6. Logging work hours spent on each individual ticket/story
It is also very helpful in creating a very simplistic boundary line between the on going sprint and the backlog (all my projects have been executed in Agile mode). In addition to it, as my projects have always had more than one sprint going on simultaneously and the stories part of those sprints related to each other, it acts as a very elegant tool for representing such views where the information is easy to comprehend for any developer or tester.