Here you can find some resources that can help you prepare with Brain Teasers. Remember the more you read the better prepared you will be.
Heard on the Street: Quantitative Questions from Wall Street Job Interviews: A famous book, that you can find as an ebook featuring famous brainteasers asked in interviews. Make sure you have a read on that
Braingle: Great site with brain teasers
Brainden : Many brain puzzles to feast you brain with
Brainbashers : Brain teasers, puzzles and games for all brains
Sharpbrains : Countless brain teasers to make your brain smarter
Brainteasercentral : Another great site to find brainteasers