I've a book called "The Tao of Zen" by Ray Grigg sitting right here on my self!
The premise of this book is that "Zen is Taoism disguised at Buddhism"
The chapters of comparison of philosophical similarities are :
Wordlessness, selflessness, softness, oneness, emptiness, nothingness, balance, paradox, non-doing, spontaneity, ordinaryness, playfulness, and suchness.
I think I was into Taoism and Zen before being introduced to Tibetan Buddhism. I think the Tao concept is similar to dharma in the idea of the way or path. The terms are different but the ideas and process are similar in many ways.
Bodhidharma is said to have brought Buddhism to China by 520AD but it is known to have been well established long before that according to this book. An interest in Taoism is said to have been revived by the spread in Buddhism as well. And at times Buddhism was regarded as a sect of religious Taoism in China.
Interesting topic! I'll be watching this thread!