I found this book in a library once as a teenager, and was so glad to find it on here. It is a collection of stories and koans from the Zen tradition. I find that some I can understand (at least a little), some are beyond me, but all engage my mind and encourage me to think in new ways. This would be a valuable tool for anyone with a meditation practice, and also an enjoyable taste of Zen for anyone.
This is a collection of 4 books: 101 Zen stories, The Gateless Gate, 10 Bulls, and Centering. If just for the first 2 alone, this book is very much worth it. The stories and koans contained in the first 2 books are timeless classics that are worthy of being in any good Zen library.