Yitzi has already sent me Light of Ephraim and I'm finding it very good and helpful so far. Thanks!
About the book : It contains some very deep kabbalistic insights into the nature of sexual aveiras while tying in lots of other areas of Torah and general hashkafa. It has helped me understand why some statements seem so scary and out of proportion, like how to understand when the Zohar says that there is no teshuva for wasted seed and other such statements. It is written in the form of a dialogue and story which keeps it also fun and gripping, and not too heavy, despite the fact that the sugyas are very deep. I am only about 1/3 of the way through, but I would certainly recommend it to anyone who wants to understand the deeper kabbalistic insights on sexual matters as well as other topics such as moshiach.