Instead of using PSA to tell me to read to my children(something I don't need to be told) How about useful ones that actually help society in more practical manners.
"Hi, this is [Insert sports star name] here to remind you that there is about 1.6 Kilometers, or 'clicks' to a mile."
"Hi, This is [Insert teacher name] just reminding you that there are 2.2 pound in a Kilogram."
"This is [Car driver] just reminding you that properly inflated tires saves lives and gas."
"Id like to take a moment that putting non violent criminal in jail costs you 50 thousand dollars a year plus health benefits, per criminal."
"Hello, this is Inigo Montoya reminding you that you killed my father, prepare to die."
"This is Garrett Moffitt reminding you that LIVE FROM NEW YORK IT'S SATURDAY NIGHT!"
I've always wanted to do that, and I doubt I'll ever get the chance to actually do it on Saturday Night Live. For the record I would be AWESOME at it. Second only to John Belushi trying to hold the show up and demanding Frasier / Ali tickets to say it.