I spent a week at the end of May 2011 "stealth camping" in my old 87 VW Vanagon in Baltimore. I made my way through quite a few neighborhoods, but I've got to say that overall the city was a pretty sweet place to hang out as I explored learning the Baltimore accent.
Baltimore = The Wire
During my stay, I actually got to talk with a couple of people who worked on the HBO series The Wire, including a few people who worked for the Baltimore Sun during the same time as David Simon, author of The Wire. A couple of them had roles on the show or served as writers and consultants.
For many people, The Wire seems to serve as the ultimate Baltimore show and is often considered among the greatest TV dramas of all time. Each season focused on a different facet of life in Baltimore, but a lot of it seemed to delve into the harder side of life in the city. If your experience of Baltimore is purely through The Wire, there's a lot of the city that you are missing.
Baltimore = HonFest
It's incredibly likely that at some point you'll be called "Hon" if you go to visit Baltimore. The salutation has existed for a long time, but it's become even more popularized due to the opening of Cafe Hon in the 
Hampden neighborhood and the extablishment of the annual "HonFest" in 1994.
Each year, there is a street festival celebrating the friendly "Hon-ness" of the city, culminating in the crowning of Miss Hon. The traditional Hon costume consists of excessive exploration of beehive hairdoos, cat-eye glasses, spandex pants and bright colors anywhere and everywhere. The AccentHelp download for Baltimore includes an interview with a waitress from Cafe Hon who was once crowned Miss Hon. I properly backed out of the restaurant after the interview, genuflecting as I exited...
There's also some frustration surrounding "Hon." There have been legal battles or threats of legal action in recent years, as the owners of Cafe Hon have claimed ownership over use of the term Hon. Longtime Baltimore residents argue that Hon was there long before the Cafe - though my lawyer has advised me to take no sides in this contentious issue!
Baltimore = Awesome People
When all is said and done, I have to say that it was the people, their generosity and their pride that sticks with me after my visit. I had an extended stay in the Hampden neighborhood and enjoyed 
becoming an honorary guest at a Memorial Day party and potluck at the Griffith Tavern. In return, I was able to buy a few Natty Boh's for some folks, and I helped to cure a guy's day-long struggle with hiccups. (Drink a large glass of water upside down out of a straw.)
I also spent an evening in a rougher close suburb of Baltimore: Dundalk. I was given directions to a friendly neighborhood bar there and got a chance to meet a number of people who make their living working on the docks and spending their weekends going "down the ocean."
I caught a street festival, had lunch with a whole group of current and former Baltimore Sun reporters, drank some beers in the Cross Street Market, and wandered along the rehabbed harbor area. I also got to record a wide range of people who gave me a good sense of the Baltimore accent so that I am able to share it on the AccentHelp site. I'd go back to Bawdimor again in a heartbeat, hon.
