Q-bank and First Aid will get you the score you need for any specialty. Next would be Step Up for the Boards, BRS Path, maybe a little BRS Physiology. If you can track down the Goljan lectures, they are also somewhat helpful, but not necessary.
Unless you know you are the type who really needs or benefits from a course I would say it is not worth it; on your own you can tailor your studying as needed. I used first aid, step up to Step 1, and Kaplan QBank and found this worked very well. I really recommend the Step Up book.
I took the Kaplan course (offered for less than half-price at our school) for Step 1 and did OK. Did QBank and USMLEWorld for Step 2 and did 40 points better. I'm planning on First Aid for Step 3 (I figure I can squeeze it in in a couple of days) and USMLEWorld Lite (offered for free at my institution) for Step 3. if you're taking a real test (the IM boards), I review course can't hurt.