When Riley approached two years of age it seemed as though he finally figured out how big he was and proceded to become a major jerk. He was bluff charging other dogs and basically being a bully as well as totally blowing me off. This is quite common when dogs mature.
What worked for us was tightening down the rules and working regular obedience sessions etc but that was
combined with lots of positive reinforcement for his good decisions. I worked hard on developing a better relationship with my dog by doing lots of obedience/recall "games" with lots of reinforcement. This causes the dog to look to me for all the "fun stuff" as well as for leadership. When you have that it becomes easy for the dog to look to you for permission to go see other dogs etc. It is also really important to work on lots of self control.
Once you have a history of bad reactions it also becomes very hard for us to maintain that calm behavior that helps our dogs in stressful situations. For a while every time we approached another dog on leash I would sing the "I'm a Little Teapot" song in my head to keep my body language loose. I would use calming signals and also be very positive, treat lots and keep the visits short. Riley loves to tug so often once we passed I would often do a quick game of tug to help us decompress.
I would also strongly suggest that you purchase a few books on dog body language. Learning to read your dog's behaviour is a huge help in heading off bad situations before they develop. I personally love
http://www.dogwise.com/itemdetails.cfm?ID=DTB527 which is also available now as an ebook. I still will use some of these signals (head turn, yawn) etc. in times where Riley might seem a bit uncomfortable with a crazy approach from another dog.
The good news is that we were able to work through the situation within months. The only time I ever really need to watch Riley now is if he is super excited or if a strange dog approaches him very close to our vehicle. I was luckier then LP in that he had a strong basis to start with as we had him from a puppy and we just needed to head off the "ass" phase before it became totally ingrained behaviour.
Good luck
.