We used to have the same problem with Abbey. She would bark to play, bark to get a belly rub, bark for just about everything. It was unbelievable that a dog could bark so much, and because she was so cute when she was a pup, we were reinforcing her by doing what she wanted. Sort of fueling the fire, I suppose. So we made an appointment with our wonderful vet and he helped us realize where we were going wrong. First and foremost we absolutley had to IGNORE her when she began to bark, and let me tell you we thought we were going to gocrazy. Once she had finished her barking spree we would give her a simple command, something like sit or down and then reward her greatly. If she began to bark again, we would ignore her again. The most important thing that we were told was to make sure that we did not reward her in any way for any sort of unwelcome barking, and rewarding her included giving her the attention that she was seeking. After a few really loud days of barking, things got much better. Now she is 2 and much more polite. She knows to speak on command, and has learned that when she gets too carried away and barks she will not get what she is looking for, infact she will get nothing at all.
Good luck!! You might want to invest in some earplugs for the next little bit... if you try this!