I've heard it can be used to hang posters. But I myself am partial to tape. You would need a lot of Blu-Tac to hang your SACD player on the wall, but I would imagine the space savings would be phenomenal. You may want to test it first by placing some absorbent material underneath the player just in case it falls. Believe me, I know - my cousin sustained a concussion when my old receiver fell off the ceiling and bonked him on the head. He has never forgiven me. Since then I always use more Blu-Tac than necessary.
I tried Blu-Tac on my CD player (technically it was yellow) because some discs would slip on the spindle. It didn't work at all. A dollop of rubber cement did the trick.