I thought I'd share what I would consider an excellent "Top Ten List: Top Devotional Books" from a great professor at Asbury Theological Seminary. Dr. Kinghorn is a professor at Asbury and, most importantly, a man after God's own heart. He is an honest, earnest man with a love for God that is evident in his teaching and his life.
I have used and will certainly return to some of the resources on his list. The others are on my mental list of ones to use in the future. Off the top of my head, my own personal list would also include:
Reflections for Ragamuffins by Brennan Manning
Bread for the Journey by Henri Nouwen
A Testament of Devotion by Thomas Kelly
This Day with the Master by Dennis Kinlaw
Enjoy Dr. Kinghorn's list. I hope it helps in your own search for a meaningful, encouraging, and challenging devotional. Feel free to share your own favorites through my blog comments!