I have an American Pitbull, she gets along EXCELLENTLY with other dogs, we take her to a dog park often for excersize and recreation and she loves to play with the dogs, but if a person comes up to her she backs up, puts her ears down, and barks.  She's NEVER bitten anyone or even made like she was going to but it still bothers me that she acts this way.  She's had owners before us, we actually havent had her all that long, so im wondering if the people that had her before us may have abused her, and if so what can I do to help her to feel better being around people?

Employ the help of friends to help get her socialised with people. Get them to be at strategic points during your walk, have them stand with their backs to the dog as you approach (this stance will seem less threatening to her) as you get closer your friends should drop small treats on the ground to get her to associate nice treats with people. After doing this many times the dog should stop barking at people, she will be concentrating on what is being dropped for her, when you've got her to this point you can then test the waters to see if she reacts if the person turns to face her, and gradually build up from there. She will be getting used to you and your family during the weeks ahead which should go someway to helping her to trust people, speed things along by inviting guests to your home (1 at a time- no crowds) When you let them into your home speak in a very friendly way (go over the top) to show her that the person is accepted, have the person give treats. You have to play a lot of this by ear and don't push things too far until the dog is ready. Softly, softly, catchy monkey as the old saying goes. :-)

How old is she now ?
Just seen her photos on your webpage - shes a sweetie :)
Do you not have any background on her from her previous home ?

Find a good obedience /training club it will help you both.

All I know about her previous owner is that they screamed a lot!  They were our neighbors at our last home and they were constantly screaming and fighting and the wife threatened to take Cinnamon to the pound, Cinnamon being the man's dog, and he begged us to take her since there is a no adoption policy here for pitbulls and she would have been put to sleep.  That's how we ended up getting her.