As so much said about PA's is negative can we have a positive thread for things the PA does?
School Link - parents get cheap books with free postage, children get encouraged to read, school gets free books.
Everyclick - search engine which gives money to school for each search. You also get money for any purchases through the site and even sometimes for insurance quotations. Ok it's a pittance, parents need reminding quite a lot and its not as good a search engine as google - but it's money that doesn't come from parents and it doesn't have the duplication that you get in google. I've found some items to purchase at lower cost from using it as a search engine.
Entertainment - it's not my thing but one PA I knew ran very popular quiz evenings and discos at a local hotel. In an area with little entertainment non-parents were happy to attend.