As 4arch mentions...you should provide a bit more info in regards to what you're looking for in a marina? Club, working marina, price range, Magothy or Patapsco rivers, etc etc...
The two rivers have very different personalities. The Magothy side is less populated and has less marinas, at least on the Pasadena side. The Magothy is a beautiful river to sail and a good place to sail when the bay is to stirred up, but similar is true of the Patapsco, add in the commercial shipping traffic though. You'll typically pay more to be on the Magothy. I am not a fan of Bodkin Creek. The inlet can have shoaling and there is a lot of Power boat traffic in there with no speed limits until you're a ways back. I am surprised the residents haven't had that changed yet?
I'm at Oak Harbor, recently named best boat repair in Pasadena. The owner is a sailor and the marina is 99% sailboats. If he doesn't know how to fix it, he knows someone who does. Here is a great article about OH, you may recognize the author, his wife writes for Cruising World magazine CBM - Marina Hopping | Oak Harbor Marina | Chesapeake Bay Magazine
They are reasonably priced and the marina is well protected.
Maryland Yacht Club: Beautiful location, well protected, quick access to the bay, has fuel, and a restaurant. As mentioned the 3rd Annual SNR will be there in a couple of weeks hosted by chef2sail. I am considering moving there next year. Just pay dues and enjoy, no need to work for your dues unlike BYC. Chesapeake Bay Boating and Sailing Clubs ~ Maryland Yacht Club
White Rocks Marina: Nice, large, new docks (ask why), and I think it has a pool? But it can be pretty ugly during a storm, hence the lower rates. Adjacent to MYC.
Fairview Marina: located behind MYC and WRM. Well protected, haul out facilities, but I think its on the higher end of $$. I have not heard many good things about the owner? But thats just rumor.
Bar Harbor: Small, newer docks, privately owned I believe, across from White Rocks and MYC. No or little space for dry storage.
Pasadena Boat Yard: Across the creek from Oak Harbor. I think is being sold or just was? Not sure what the deal is but there is activity there, so they may have a slip. Its mostly power boats though.
Hammock Island: Beautiful privately owned marina on Bodkin Creek on its own little island. All sailboats. There is typically a wait list. I would go there but I think the maximum LOA is 37 ft? One can be bounced around a bit from all the power boat traffic on a busy weekend. Hammock Island Marina
Geislers Marina: At the mouth of Bodkin, don't know much about it. To exposed for my taste. Not sure what the rates are, no one would ever return my inquiry.
Germershausens Boat Yard: Small place, not sure what kind of depth there. Mostly or all small power boats
Ventnor Marina: Always full, mostly power boats. Um, maybe thats why they always tell me they're full after I tell them what kind of boat I have? Ventnor Marine Services - Best on the Bodkin!
Bodkin Yacht Club: Very protected, Dues are minimal. You must work something like a minimum of 75 hours a years and bartend twice a year? New docks, a good friend is the Fleet Captain there if you're interested.
Pleasure Cove Marina: New huge indoor storage! The marina owner has an obnoxiously huge power boat, you cant miss it and its dingy. Has a small store and ok restaurant on site. Its located just next to BYC. Pleasure Cove Marina - Pasadena, Maryland full service marina.
Gibson Island Marina: I think you have to be a resident of the island or know someone to get in. To far back IMO for a sailboat anyway
Atlantic Marina - Magothy: Used to be called Pleasure Cove, then Gibson Island Marina. Has fuel, great location, but mostly power boats. Inlet can be shallow. Kept my first sailboat there for a couple of years. My Uncle is a slip holder so I know it well. Owned by Atlantic Marina Group now.
Bodkin Marina: The cheapest around that I know of, and for good reason. (This is not to be confused with Bodkin Yacht Club). I spent a season there for $1200.00 and that was to much to pay for that facility IMO
Atlantic Marina & Resort: Don't know much about it except that is home to many cigarette type boats. The company that owns it has purchased several marinas in there area of the past few years. I'm not even sure the tiny inlet into the marina will accommodate any kind of draft?
There are two other places to tell you about, send me a PM for more info.
For some good aerial views and more information try here: Marinas.com, World's Marinas Portal, and Marina Directory