These passes were a huge success in my classrooms. I would keep a stash of them in my "prize box," and students often chose them over school supplies and other fun items (and it didn't cost me anything!)
The homework pass is good for one missed homework. If a student has this pass, they can choose to hand it in instead of an assignment on any given day (with some exclusions like drafts of major projects, etc.) In addition to having this in my prize box, I would give one to any student who completed all their homework within a marking period. This product includes a visual to be hung on the board near where homework is written to encourage students to complete their assignments.
The other pass allows students to do other constructive, quiet work during independent reading if they want a break from their books.