Blasphemy is the most obvious, though. And it currently already acts like one.
Blasphmey does not currently act like a meta gem, it acts like (and is) a regular support gem. It does nothing at all by itself, and just applies changes to each supported skill individually.
It will likely be reworked to a meta gem in PoE2, but that will involve a significant change to it's functionality, including probably making it a skill-support, like Spellslinger will be and Bane already is.