a few ideas i remember from previous years:
not sure how old your child is but i remember students hosting a luncheon. the school/pta paid for the food to be catered but the kids set the tables, served, cleaned up.
if the staff is small enough, students can present mock awards to teachers.
personalized mugs
or, you can design/order personalized READ posters from ala (american library association.) (also a cool reward for kids. they'd become famous!)
gift certificates or goody bags of office supplies. we spend oodles of money on school supplies each year. you can find out at school what is in the supply closet (so what the teachers get for free at school) and what's not. things i loved: stickers, colored chalk/dry erase/overhead markers, colored paper, electric sharpeners, good hole punch machines.
there might also be a teacher supply store in town...though those are better for elementary school teachers who can use their cool things more often.
and, yes, gift certificates to food (someone mentioned panera), bookstores is always a nice treat.
:)rachel