Post your Minetest tips here!
I found one while mining in darkness. No torches needed.
While playing on c55.me I found myself in a cave with no escape, the only way out I expected was building one node out, however, I got truly stuck and could no longer do anything, so, too see where I was headed, I turned my "gamma" setting on my monitor to see in the pitch blackness of the cave, so, torches are actually useless by hardware standards.
EDIT: You can post 'em as well.
