
You can also track the lead and cycle time for features in the product backlog.
Lead time is the entire life of a feature from the time it is added to the backlog to the time it is completed. The Cycle time is from the moment action is taken on a feature to the point where the feature is completed/delivered.
These are a bit more common in Kanban but would work in a few contexts.
Also, I have to echo what others have said here. We should be very careful with our metrics. They can have unintended consequences. Such as cutting devlopement or testing corners to get something out before the next release. One way to combat this is to balance a metric that follows productivity such as task or feature completion rate over time and compare that to a quality metric that measures bugs, rework, or customer satisfaction.