When we are working with aggressive dogs that need a quicker fix we occasionaly allow the problem to exstinguish itself.
As an example, last night I was working with a very leash aggressive beagle/rott mix (off leash this is a great dog). I started the training session by doing basic obedience work (sits, downs, stays, comes, heel, etc.). After the dog started to tire (takes about 15 minutes of solid obedience work), I brought one of my dogs into the picture (a very confident, well trained shepherd).
Both dogs are introduced on leash, and are kept a foot apart by each of the trainers. Of course the beagle went to his antics of barking and snapping like a maniac. The dogs are kep a foot apart until the beagles stops barking and snapping (this took about 7 minutes...a very long 7 minutes). After the beagle camled down the dogs went there sperate ways and were given 10 minutes to relax. Then we did the same procedure again (this time the beagle mix calmed in about 4 minutes). Then we did it a third time (down to about 45 seconds). The fourth and final time the begal no longer reacted to the dog, and they were allowed to socialize (very closely supervised).
Each day I will do this procedure with a different dog and the beagle mix. By about day 10 there will be little or no reaction to any dog at all.
We have been using this process for about a year and half and have had great results.
The reason it seems to work so well, is that most leash aggression is fear based, and once the dog realizes there is no danger he gets over it. Unfortunately, most people take the opposite approach, where everytime the dog goes into it's frenzy it is removed from the situation. The dogs goal from the beginning is to get out of the situation, and when we make that an option the behavior continues.
I recomend that if you try this procedure you have a pro on hand to help so no mistakes are made. Let me know how it goes.