Psionics: A New Old-School Supplement (2010)

From the Introduction:

Hello fellow adventurer!

If you like old school gaming and wanted psionic powers in your game, you found yourself in a rough position. Or perhaps you’re familiar with looking up a monster to discover a listing for psionic ability, only to discover those rules don’t exist. Perhaps you’ve decided to use the rules as written only to find a certain select set of issues with the rules. And at that, I’m being kind.

And yet the desire persists! Psionics! Strange mental powers! Psionics fits exceptional well with the old-school pulp gestalt of Dungeons & Dragons. The thought of great mental minds in conflict, an energy separate from magic, powerful, yet fraught with danger! So therein lies the reason for the creation of this supplement.

This supplement/sourcebook is available as a free download from the author's site.