Once upon a time I was a teacher.
So, you know, teacher gifts just seem very right to me.
Don't worry. The goal here is not extravagance, it's acknowledgement of a difficult job involving a lot of small people. It's thankfulness that someone besides you is willing to commit to your children.
Places like Target and Michael's are great for finding fun, appropriate teacher stuff and gift wrap. The days of apple mugs and teacher poems are gone. Stick to practical, useable items or gift cards.
Have fun wrapping it up and get the kids involved writing notes of encouragement.
Go with a theme.
Give a seasonally appropriate hand soap for each holiday or start the year off with a napkin holder and then give seasonal napkins throughout the year (Darla's idea!).
Or if all this just sounds like too much, find out favourite drinks and bring a Starbucks or Tim's to teacher conferences.