I present my tacky solution to firmly holding my mic overhead boom arm. The block of wood is actually one I broke in my black belt test and it helps protect the particleboard desk from damage from the clamp.
The couple coupons are there to give a little extra balance to keep the mic boom completely vertical and prevent it from drifting. This is actually my cohost's mic, which is at the back of my podcasting desk, so the surface is a not completely level.
What tacky solutions have you found that work perfectly for you?