I know this is a dated post, but I've some older gimmicks and systems as well as a new look at mentalism of late and have some suggestions for you Princess (and/or others if you've satisfied your mentalism query by now).
Here are some gimmicks that generally fall within the realm of mentalism:
These aren't books, but can supplement a mentalist act
Superman Coin Bend or the
Boa Coin Bend.
Both of these yield the same basic result. Both gimmicks have their pros and cons, but I personally prefer the Superman. It takes a bit of strength, but with practice you should be able to get a result.
Vernet Writer or
Swami Gimmick
I have the vernet writer and am happy with it. I've not used the swami gimmick that attaches to your thumb nail, but imagine it would be an option for those who have long fingernails that would make the vernet writer more obvious. I've heard good things about
Lincoln's Best Boon but have not used it myself either.
Books
Sleight of Mind - Ian Harling and Martin Nyrup
This goes into NLP as it applies to mentalism. The book is more for someone who wants to become a student of mentalism rather than a short cut for the mind controlling wannabe. If you're looking for copy & paste mentalism routines - this book isn't what you are looking for. If you want to develop a mentalist act - I'd pick it up.
These guys have another book out on mentalism as well, I don't own it yet and not certain if/when I'll add it. I think the title is Geist if you end up finding their books to be helpful.
Neuro-Linguistic Programming for Dummies
Don't laugh at the title. I know the "for dummies" books tend to catch some flack at times, and it's probably not where one would generally go for their magic needs but I recommend you buy this book.
You'll also hear the nay-sayers complaining about NLP. Some of their criticism will be valid, others are off-base. NLP may be complete Barnum bunkum, but so is "magic."
This book is pretty dull and reads like a textbook, but it will give you a better grasp of what many of the Mentalist texts are trying to project. It is also a good foundation for creating patter for your mentalism routine...
Draw me a Tree
There are text versions as well as DvD versions of this system. Pretty much cold readings, but allows you to get into mentalism and readings without having to get into Tarot, Runes, etc that have a certain taboo about them.
Bionic Mnemonic
Part card magic, Part mentalism. No sleight of hand or card control needed at all. You do need a partner.
Some of these systems are out of print or in limited circulation. If you're interested I may be able t get a copy of one or more into your hands. If you have any questions, feel free to message me direct via clown mail.