How much does a US Navy doctor earn?

That completely depends on a number of things, the biggest being your rank and bonuses. If you're a doctor, you'll enter the Navy as an O-3, you'll generally be promoted to an O-4 within 5-7 years after that. The bonuses largely depend on whether you're board certified and the type of physician you are. These bonuses can range between $15,000/year - $100,000/year.

Most physicians who enter the Navy go the HPSP route so they get medical school paid for, however, there is naturally a service obligation for this. However, if you're looking for the military style mixed in with medicine, you can do some cool things like Dive Medical Officer or Flight Surgeon. These also give you special pays.

You also need to take into account where you live, because your BAH will vary greatly.

Generally speaking, through the HPSP route -- strait out of medical school you'll make around $100,000 a year (which trumps a resident's salary any day). However, after you're finished with residency and you're board certified, this will increase to atleast $150,000-$200,000/year depending on the type of physician and rank. These latter salaries are largely paid through yearly bonuses.

If you go into the military as a physician, go in for the reason that you want to serve, not for the money. Doctors outside make far more.