Possible uses of the choice activity include:
Choice is a secure way to gauge understanding of a topic without asking students in public. The teacher only will see their response. You may also wish to allow them to update their choice, to show progression in their understanding and confidence.
A simple attendance register or course agreement
A choice with only one option may serve as an attendance record 'I am present' or a course contract 'I have read and understood the conditions'
Project/Group sign up
Students may be presented with a selection of future projects and they can select one. This could also work to as a group selector, although Choice itself will not put them into a group. There is a contributed module Choicegroup
Choice can be used for student council or student union elections.
Teachers can even make choices for students who don't respond, as shown in the screencast Choice responses by teachers.