Besides dips skull crushers
weighted dips? I just use chains, looks damn cool at the gym. I use skulls too, and push downs sometimes rope, usually straight bar though.
from my personal experience i have found most gain from tricep push downs at the cable machine, try 4 sets, going to failure each set, starting at 10 reps, up weight, down to 8.. and then down to 6.. and for the 4th set drop weight about 40% and rep to failure.. that will give you a good burn,,, oh and only rest about 60 seconds between sets
