Think outside the box of social events for the kids and gifts for the teachers. Are "PTOs" part of the national PTA organization? If so, any school can participate in a national PTA program called Reflections (go to http://www.pta.org/2032.asp). The PTA/PTO at the local school level sponsors it for your school.
Reflections is a national arts program. The kids are given a theme (for 2012-2013, the theme is "The Magic of a Moment") and the kids do some form of art on that theme -- it can be visual arts (drawing, painting) or it can be a short film, an original dance, a musical composition, a poem, story or essay. The national PTA has rules about things like length of a dance or song, or size of paintings, but the kids really have total leeway on how they interpret the theme. Then the school finds some local judges (teachers at other schools usually are very willing to be judges) and has judges decide which entries in each category are the outstanding interpretations. Those entries move on to judging at other levels (county PTA level, state, national).
It's a competition, yes -- but the emphasis is very strongly on just having kids participate and be creative! We have had success with getting more kids to participate each year. Kids do this totally on their own, in their own time, and it gives them a huge sense of achievement whether or not they get an award at the school level. We have a nice PTA-sponsored event in the evening, invite all the participant kids and their families, and display every single work of art; every piece of literature; have the dances playing on a DVD loop on a laptop and the musical compositions playing on a CD; and so on. There are refreshments and then awards -- parents love to come, bring the siblings and grandparents, and take photos as we call each child's name to come up and receive a participation certificate or award medal. You definitely don't have to have as big a ceremony (our previous school did it during the school day and just handed out lollipops --not my choice but cute -- to everyone, and medals to the three levels of judged entries, and that was it). But the best thing about Reflections is that it gets kids who otherwise might not think they're artistic or creative and gives them a place outside art class or music class to express themselves with no one telling them their ideas are right or wrong!
Another thing a PTO/PTA can do is "cultural arts" assemblies. Kids at our school LOVE these. These can be almost anything you want and can find in your area. Here are some we've had, though what you could do depends on what's available in your area and on your PTO budget:
--Fourth grade saw a baking demonstration by a person from the King Arthur Flour company; King Arthur provided all materials for every fourth grader to take home a bag with two kinds of flour, yeast, and directions to make two loaves of bread, and kids brought back one loaf; the loaves were donated to a local food bank. I believe King Arthur does these events for free.
--Fifth grade heard a terrific presentation about medieval grave brasses (brass portraits) and then did brass rubbings of some beautiful copies of real brasses from England. A firm in the US actually does this kind of presentation just for schools!
--My daughter's dance school and other dance schools in the area perform for local public schools as part of a program called CAPs (Creative Arts Program). CAPs brings dance, music and drama into the schools directly. PTA cultural arts program chairs decide about booking CAPs acts for their schools. If your school system does not have something similar to CAPs, why not try having your PTA find a local small dance troupe or good dance school willing to come do a show? (Or bell ringers, or the city chorus, or a theatre group, etc., etc.)
Those are just a few of the kinds of things PTAs/PTOs can do if they try. We love the ice cream socials and movie nights and stuff, but it is great to do more enriching things that either feed the curriculum or expose kids to new things like baking or dance performances.