First, read this.

Bernard Lewis is outstandingly good. I recommend his ‘The Crisis of Islam’.

Also:
Roger Scruton, The West and the Rest (good description of why the Western culture is both different and superior to alternatives, reflecting Christian roots)
Daniel Pipes, Militant Islam Reaches America (solid)
Robert Spencer, Politically Incorrect Guide to the Crusades (excellent, a must read, shatters illusions)
Karen Armstrong, Islam, a Short History (good statement of conventional opinion; remarkable whitewashing of controversial elements)
Maxime Rodinson, Muhammed (solid; written before PC became rampant)
Oriana Fallaci, The Rage and the Pride (strident, striking, bracing, refreshing)
John Gray, Al Qaeda and what it means to be Modern (best philosophical analysis of the situation that I have read)

On my bookshelf yet to be digested:
Oriana Fallaci, The Force of Reason
Bat Ye’or, The Decline of Eastern Christianity under Islam
Norman Daniel, Islam and the West
Andrew Bostom, The Meaning of Jihad

Good websites:
Daily Briefings on Iran
Jihad Watch
Daniel Pipes
Informed Comment