GURPS Powers (2005) expanded the rudimentary example of psionics in the Basic Set to the full 4e powers system. In GURPS a "power" is a set of related abilities that share a source (the energy that the power uses or manipulates) and a focus (the specific concept the power is themed around). Mechanically they have a Power Talent that adds to rolls to use the abilities of the power, and the Power Modifier: a shared modifier (typically a limitation worth -10%) that defines the limits of the power.
I've run (or at least started) a few different games since Powers was published, some like my new weird road-trip Desolation Road and my Transhuman Space technothriller Hearts of Oak, Souls of Fire, didn't use powers at all, but the rest did.
