I would spend it on entertainment like bringing in some educational speakers or having a going away party for the school with some entertainment.
How about a nice field trip.
Have you considered iPod Touches? I was skeptical, until our Tech Specialist gave a demo of all the educational applications the students can use. The best part is that the apps progress with the student, so if a student needs more work, the app stays at the same level of difficulty, whereas a stronger student can move along.
Our PTO has been raising money towards a certian goal for 2 years. The goal was for some specific building imporovements. Now our district is talking about consolidating some schools and we don't want to do physical improvements on a building that we may be moved out of shortly. We have decided that we want to spend the money of something the children can "take" with them. Programs to come into the school, etc. Our PTO is made up of a few mostly working mothers that don't have a lot of time for coordinating/planning. Any suggestions?