What usages besides manifesting psionic powers exist for Power Points?

Question

Psionic characters spend Power Points (PPs) to use their powers, and this is the main usage for these points in the game.

A character with the Wild Talent feat will obtain 2 PPs; also many psionic races have some extra PPs naturally. In both cases, they don't get the ability to manifest powers - so, unless they got levels on manifester classes, these points will be of no usage.

So, what usages besides manifesting powers exist for power points?

Answer 1

Including Brian Hellekin's answer for completeness sake.

• Elan racial abilities are powered by power points [SRD]
• Pyrokineticist's Firewalk class feature [SRD]
• Becoming psionically focused [SRD]
• the Psychic Renewal feat from [Tome of Battle] allows you to recover expended martial maneuvers by expending power points.
• some items allow the expenditure of PP to power their effects, such as the Shroud of Oblivion [Complete Psionic]
• this includes cognizance crystals which can be used to store PP [SRD]
• a weapon made of deep crystal can be powered to deal extra damage [SRD]
• the psychic weapon property grants the weapon an enhancement bonus based on how much PP the wielder has in reserve [SRD]
• a galvanic crysteel blade can be charged with PP to augment its damage [Magic of Eberron]
• the Strenght of Two feat [Races of Eberron]
• the Kalashtar Thoughtshifter feat [Races of Eberron]
• the Kalashtar monk and soulknife substitution levels which grant several class features that can be augmented with PP [Races of Eberron]
• same with the Quori nightmare PrC [Races of Eberron]
• the Illithid blast feat that mimics illithid's mind blast is powered with PP [Complete Psionic]
• the Lurk psionic class powers Lurk Augment abilities via power points [Complete Psionic]
• the Ebon saint has a similar augment mechanic [Complete Psionic]
• the Synad's Multitask racial ability is powered by PP [Complete Psionic]
• the Soul manifester can augment his essentia pool with PP
• the Magical trickster can be adapted to be psionic, in which case he can power his tricks with PP instead of spell slots. [Complete Scoundrel]

The answer does not include Psi-like abilities or class features that copy powers or manifesting powers as part of other processes(for example scribing psionic tattoos or psionic item creation).

(there may be other instances I've missed)

Answer 2

I found a few usages, although they're very specific to certain races, classes and feats:

• Elan: Elans can spend some Power Points to use their racial Supernatural Abilities:

  Resistance (Su): Elans can use psionic energy to increase their resistance to various forms of attack. As an immediate action, an elan can spend 1 power point to gain a +4 racial bonus on saving throws until the beginning of her next action.

  Resilience (Su): When an elan takes damage, she can spend power points to reduce its severity. As an immediate action, she can reduce the damage she is about to take by 2 hit points for every 1 power point she spends.

  Repletion (Su): An elan can sustain her body without need of food or water. If she spends 1 power point, an elan does not need to eat or drink for 24 hours.

• Pyrokineticist: at the 6th level, the Prestige Class Pyrokineticist gains the ability Firewalk, which allows him to walk in the air, spending 1 PP per round of travel:

  Beginning at 6th level, as a free action a pyrokineticist can expend her psionic focus to literally walk on air. She moves at her normal speed in all directions, including vertically, but cannot move more than double her speed in a round. A firewalking pyro leaves footprints of flame in the air that disperse in 2 rounds, but her tread does not deal damage. She must pay 1 power point per round spent traveling in this fashion.

• Psionic Focus (usage of the Concentration skill): Having at least 1 PP is needed to gain Psionic Focus, which is needed for many Psionic Feats:

  If you have 1 or more power points available, you can meditate to attempt to become psionically focused. (...)

  Once you are psionically focused, you remain focused until you expend your focus, become unconscious, or go to sleep (or enter a meditative trance, in the case of elans), or until your power point reserve drops to 0.

  But none of the SRD Psionic Feats spend power points itself, so this "usage" will not required the character to spend PPs - it's only a matter of having at least 1 power point.