A Little History of Philosophy
A great introduction (or re-introduction) to the history of Western philosophy.
The most important philosphers and schools are discussed in an easy-to-read manner, usually in no more than six pages. The tone is so simple and friendly that it would be a good read for teenagers as well. The chapters are nicely sewed together, but they can be read independently as well. Given its short length and plain style, it could be called simplistic with good reason, but who cares if it actually makes you stop and think?
I like it a lot.