Most styles have palm strikes in them at some point or another. In Hapkido, most of our advanced strikes use open palm instead of closed. I believe they come from Tae Kyon, which is a Korean style of almost soley palm strikes and intricate foot strikes. Lots of unique stuff there. But, I don't think you can easily find a Tae Kyon instructor anymore. At least, not one who teaches it exclusively; it's a pretty obscure and almost lost art.
There are no PERFECT techniques, only perfect execution for the situation at hand. ~Corwin