The best one I have heard is at Eureka, if a student meets or exceeds
they are able to leave 1 period early or arrive 1 period late as a
senior (if they have the credits to do that of course, and a kid who
meets and exceeds is probably on track with enough credits)

In the past two years, I have offered a couple of open lunches for students
doing well on the PSAE. Our scores have been relatively solid for three
years now, after three previous years in decline. I am going to open this
much wider next year by offering as much as a month of open lunch. We'll
have to see if there is increased improvement or not.

Our off campus privilege for seniors is supposed to be linked to meets and exceeds; however, that would require scores prior to spring time. I do not know if it has increased our scores or not but whatever we have done has lost its effectiveness as a result of this year's late arrival.

I have no way to prove this, since we have offered it ever since the
required testing began, but our kids take it seriously. We actually
start it with freshmen - they take EXPLORE, sophs take PLAN and of
course juniors with PSAE. We divide the kids into groups of about 20
for the testing, and the group with the overall highest score ABOVE THE
STATE AVERAGE earns a 1/2 "free day." That equals 4 consecutive periods
that can be excused (with some caveats - can't be on a day with a test
or other special assignment, must get all signatures and turn in work in
advance, etc.) between October 1 and May 1 of the following year. This
time does not count against kids for semester exams. (One part of our
exam policy is no more than 3 excused absences per semester). We have
found that this does help keep kids who may finish early on the
standardized tests to stay interested and quiet, because they have just
as good a chance as anyone else in the group to earn that free time off.
It is kind of interesting to watch the kids eyeball the group
demographics when I post the testing groups a couple of days before the
tests. They stand there and count up "smart kids"!!! in their group to
see if they have a chance! The counselor and I work pretty hard to keep
the groups balanced so the chances are equal. Some years the difference
in scores comes down to decimal points.
We throw in one more carrot - each individual student who earns "Meets"
or "Exceeds" on EVERY test category on the PSAE will earn an additional
1/2 "free day" just for that individual. So if a kid does well
him/herself and the group does the best, a student can earn a whole
"free day" off of school the next year. And if your group does crummy,
oh well, you can still earn your own 1/2 day.
We just take the hit on attendance when kids are gone. It also helps
stop parents from lying when kids want to go hunting or pick up their
prom tux or get their driver's license, etc. They know they have a
"free day" to use for that. It is sort of like a teacher's personal
leave, I guess. Works for us!