Psionic Power
Psionic Power is one in a series of class-focused supplement books released by Wizards of the Coast for Dungeons & Dragons 4th Edition. As the name says, the book is all about expanding options for the Psionics classes - Ardent, Battlemind, Monk, and Psion - in the form of new exploits, variant class features, Paragon Paths, Epic Destinies, feats, and other miscellaneous goods. Equivalent books for the other sources were Arcane Power, Divine Power, Martial Power and Primal Power.
It shares the unique trait of being one of only two X Power books that actually covers every single class of its associated power source (the other being Martial Power).