If you want the credits, you can pass them through an accredited transfer service, which will evaluate them and make them US-compatible credits. I can't remember the name of a specific service right now (there's one in Minnesota that has Minnesota in the name, but I don't remember what it is), but if you ask a study abroad advisor about it, they might be able to connect you. There's a fee for the service, obviously, but it'll let you use your credits.
Edit: Here we go, there's a lot of them - see which ones your school would like if you want to try it. They're listed at: http://www.aacrao.org/international/ http://www.naces.org/ http://www.aice-eval.org/
You'd be looking at a course-by-course eval, which one of them listed at $190. They evaluate the classes, decide what they equal in the US system, and then recommend how they should transfer to your school. Obviously, the final call is your school's, so you should consult with the registrar to be sure that your school will accept the recommendation before you shell out for the transfer.
I was actually wondering about this too - I just got back from a program abroad where I took an intensive language course. I got an A- in the class, which will actually pull down my otherwise 4.0 GPA. I was thinking about just not transferring back the credit (and have already been given the green light by my undergrad institution to do this) and then reporting it as an extracurricular activity rather than as a class on my AMCAS application so that my GPA on my application will still be a 4.0. Does anybody know if that's allowable or if that could get me in trouble with AMCAS?