General:
* What is the most gnarled tree you've ever seen?
* How does the gnarl of a tree affect its strength and stability?
* Can you describe the feeling of running your hand over a gnarled piece of wood?
Figurative:
* What kind of person would you describe as having a "gnarled" personality?
* Can a piece of writing be considered "gnarled" in its style?
* What are some examples of "gnarly" experiences that have changed you?
Specific:
* What are the different types of tree gnarls and what causes them?
* How do woodcarvers use gnarled wood to their advantage?
* Is there a difference between "gnarled" and "knotted" wood?
Let me know if you have any more ideas!