Powerstones
After a few years, the psi-board noticed that powerstones in the XPH/SRD have a loop.
3 times through - make Psicraft check DC 15+power level , 1 full round , draw AoO
and you activate a Powerstone without discharging it.
The powerstone has to be on your list, and no higher than your normal level.
Commentary - this is useless during combat, as in ditch 3 full rounds of activity, to gain 1 casting of X.
Immediately this was recognized as very powerful, but only out of combat.
It is by far the simplist recharge set-up, in that there's no recharging at all, just well planned use of a powerstone.
You are down 1 feat, and a small pile of cash + exp. No much of a cost vs. the return on the investment.
CPsi nerfed strangely a small collection of powers and the powerstone trick.
None of the nerfs were well received by the psi-board, except for the powerstone nerf.
What absolutely does not go away,
is the exact same loop, without the powerstone, can be done on a follow psionic manifester.
http://www.d20srd.org/srd/psionic/psionicPowersOverview.htm#manifestAnUnknownPowerFromAnothersPowersKnownTechnically the powerstone version is more expensive, and therefore not as overpowered.
CPsi didn't nerf the "manifest An Unknown Power From Anothers Powers Known".
Personally I like it so I keep it.
Otherwise its easy as pie to do it without the powerstone, just have it on the list.
2 Character with the same Hidden Talent feat.
Go back and forth between the two, never spending a powerpoint.
The powerstone version ends up being s slight nerf on this.