Goals accomplished. Its vague, but if you're at a startup (or coding for fun / to learn), perfect. Goals can be bugs squashed, features added in, performance gains, whatever you need. Its yours to mold when you start for the day and destroy when you end for the day.

If you're at a more established company, then chances are, they'll care about things getting done, but on a day to day basis, will have a different metric to use. Which is the angle you're coming from, I think.