As it was pointed out earlier, current M-theory postulates eleven dimensions. Interesting reading material regarding dimensions can be found in Flatland by Edwin A. Abbott. Issac Asimov considers it the best work as an introdiction to thinking about dimensions. The Dot and the Line, a romance in lower mathematics, is based on this book. Another fascinating work dealing wtih the time dimention is An Experiment With Time, by J. W. Dunne, a Brittish aircraft engineer. Also, the appendix on etrnality in *Basic Self Knowledge *by Harry Benjamin is extraodinary. And if your intellect is up to it, *Wholeness and the Implicate Order *by David Bohm is a must, as it treats as well of the current fragmentary nature of our thinking, which leads to the misperception and faulty assesment of experience.
There are as well some books on the fifth and higher dimentions from various esoteric writers that will be likely shunned by the pious, which neverthless contain important ideas.
For sheer fun in the form of science fiction, social commentary, and time travel, I recommend R.A. Heinlein’s Number of the Beast, which has an entirely different and intriguing take on the legendary trippple digit.