My chapter has points and uses them in a similar way. Each week, Exec chooses an event (maybe two) that are point events, like attending a non-mandatory sorority function or a sister's concert. There are also other things you can earn points for, such as being on Exec, filling out a professor evaluation for our files, wearing your pin on a day other than the day of chapter, etc., etc. At the end of the term the person with the most points gets a prize. In the past we have had massages, letter hoodies, and letter message boards (which I won!!!
) as prizes. We also use them to determine things like living in the house, etc.
I think points are pretty much a Pan-Pi Phi thing. Our Efficiency Chair is in charge of points.