oh yeah and the CHESS HOUSE series really impressed me.
all the books are in 4 languages english, russian, german and italian.
book 1 - for players just learning the game (< 1000)
book 2 - for beginners who are comfortable with 1 move tactics (< 1500)
book 3 - advanced tactics (1600 - 2200)
book 4 - endgames (1300+) this book covers 600 "standard" positions and most are annotated (there is a test yourself area at the end of each section, with solutions in the back). It includes standard endgame theory which is why its useful for everyone, but has more difficult positions as well.
http://www.amazon.com/gp/product/5946930206/sr=1-1/qid=1153896643/ref=sr_1_1/002-6898626-9449638?ie=UTF8&s=books