Derren Brown - The Devil's Picturebook. Widely recommended, and rightly so. Has several types of forces in there.
Seconded. This dvd has to be one of the best magic purchases I ever made. Love it.
Also, Daniel Madison has an ebook coming out soon called Psycho, which is purely psychological forces, or so I am led to believe. You might want to pick that up when it pops by.
Alternatively, you could get something that appears to be a psych force but isn't. From what I hear, Dee Christopher has something like that in his latest ebook, 23:23. It's a way of switching out a prediction card for the spectator's named card. Don't quote me on that, though. And, whilst this would work for a simple think-of-a-card trick, it wouldn't work for a more complicated psych fore routine, not to mention the fact that you don't get that warm fuzzy feeling that a correctly performed psych force gives you.
There's the best things I can recommend right now. Quite a few places mention them in passing, for example David Blaine's book, Mysterious Stranger mentions one or two, but those are the only places I can think of where you'll really get taught what you want. Best of luck with psych forcing, it's great fun.