If you have ever had someone look at you with a confused look on their face and say "Psionics??", then this is the book to hand them.
This book provides the basics of "What, Why and How" and you supply the "Where" by simply converting it to whatever rules you are using. Want to add "Psychics" to your Buffy:TVS game? Want an alien race in your Star Trek game to be able to Teleport? No problem.
This book would be especially good for a d20Modern: Agents of Psi setting since it includes Psionic technology to be used by (and against) psis. This book is also good for just reading, but is even better for inspiration to add to exisiting Psi settings.
[5 of 5 Stars!]