Baltimore isn't exactly the south, so for those with a love of good pulled pork, Andy Nelson's is the place to go for consuming vast amounts of animal protein. It's actually up in Cockeysville, so it's a bit of a drive, but well worth it. I'm lazy, so I will direct you to their web page, http://www.andynelsonsbbq.com for directions (you can also join the Swine Social Club, if you like). Owned and run by former Baltimore Colt Andy Nelson, it's been turning out some pretty good barbecue for 22 years. These days, Andy Jr. is around a lot more than his father, but you'll see Andy Sr. from time to time - he's pretty easy to identify, being big and tall (and old). The first time I saw him, I overheard two people behind me talking. "He can crack a walnut in his hand." I don't doubt it.
Anyway, you're not coming here to see Andy, you're here to stuff a lot of hog in your mouth and wash it down with sweet tea. The pulled pork sandwiches are probably the best bet overall, but the ribs are also very good. In previous years, the ribs were slow cooked, but I've gotten the feeling that in the last year or so they have been boiling them for a while first (which is not too bad, but does make them somewhat tougher). The baked beans are sickeningly good, I've never seen, tasted, or heard of any as good as here (I'm sure this will get me lots of downvotes from Bostonians...) The coleslaw is... well, it's coleslaw. Not much you can really say about it, is there? They also serve brisket (never tried it), catfish (really good), and pulled turkey (not bad). If you're vegetarian or vegan, you're obviously SOL here, and those with religious objections against eating pork will have rather constrained dining choices. You can get ketchup and/or mustard based sauces, which is nice (it can be hard to get mustard based sauce outside of the Carolinas).
Andy's has won a large number of awards for best barbecue from City Paper and Baltimore Magazine, including winning the Readers Choice awards for Best Barbecue from both publications this year.
As an added bonus, there is a Krispy Kreme down the road about a mile; people driving back to the city from Andy's can stop by, pick up a hot dozen for dessert, and get even fatter. It's lots of fun.