We used a bulletin board where we had a VIP theme. Each month we put a picture of one of the volunteers along with a bio that included family, hobby and other fun info.
We had a mystery teacher bulletin board. We sent a questionaire to all the teachers asking their favorite color, food, book, etc. We then typed up the sheets (minus names) and posted 8 of them on a bulletin board with silhouette & ? (printed off clip art) above them. We had a table with a bucket for guesses beside the board and gave small prizes to the top 5 people who got the most correct. It seemed to be a big hit with the kids.
Then, we made a candy bar poster (found on PTO Today under Teacher Appreciation ideas) to put in the teacher's lounge.