If I know exactly when the activity is going to end, I put that date in. For example, I am an active member of my sorority for four years, so I put May 2002 for the end date because thats when I am considered alum. Other activities that I know when the end, such as my summer job (May 2001 to Aug 2001), I also put the appropriate dates on those. I figured that people will be looking at my application for several months, and I dont want to keep sending updates and changes.