I give out one page per student per semester. I tell them that once they're gone, they're gone. They can borrow one from a friend, buy them, sell them, whatever they need to do but they can't leave my room without one. I also give them 10 bonus points for each unused pass at the end of the semester.
I simply have the students fill out the information then I put the time and initial it. It acts as their hall pass as well as a reminder of how often they leave the room.
There are two forms here with 6 and 8 passes both in PDF and Publisher form.