I have singled out birth control because of religious views. Millions of people have religious views that they hold deeply, and that does not comport with participating in a plan that covers birth control. And prior to obama's arrival they were free to exercise those beliefs, as was every American.
I don't think there should be a restriction on what an individual includes in his policy.
Off the top of my head
Check ups, shots for children, screenings for diffrent types of cancer, counseling for domestic violence...
As you said, individuals who have religious issues are free to not purchase the employeer insurance. However we have a separation of church and state, which means in part that we don't allow someone's religion to dictate national medical issues. A panel of medical experts decided birth control should be added to the list of "preventable medicine", and preventable medicine is what is mandated.