In early 1943, pilots of 5./JG 11 developed a new technique for attacking large bomber formations. They used a 250 kg bomb with a 15 second delay fuse. They would drop the bomb from about 1 km above a bomber formation, with sometimes spectacular results.
I have no idea how many units used this weapon but I do know that it immediately attracted the attention of OKL and was adopted by JG 26.
The delay fuse was also used for ground attacks. I have read two accounts by Schlact pilots who described a technique for attacking enemy armor whereby the pilot would fly towards a tank with barely sufficient height to clear the top of the turret. The pilot would drop his bomb at the last moment and pull up sharply. The bomb would slide towards the tank (sometimes under it) and the delay fuse gave the pilot time to get clear before the bomb went off under or very near the tank.
Allowing AH pilots to set a fuse delay time on the ground before takeoff would enable both of these techniques and would IMHO be a nice addition to the game.