I posted a while back about McKinnon's carrying perfect-sized pieces of salt cod and also mentioned I liked their frozen shrimp. YumYum requested a bit more info...
What I like is that they carry 2lb packages of good quality frozen shrimp. The price is about the same as TJs 5.90/lb for 26/30 and more than Market Basket. Today they had the 26/30s for 5.90, a whole bunch of 41/50 for around $3/lb easy-peel, colossal or super colossal (about 12-15/lb) for just under $10/lb. Mostly black tiger, but possibly others. Plenty of cooked shrimp too.
I like them better than TJs and Costco. The Super88 has a lot more selection, but for me is less convenient, and they tended toward 4/5lb boxes which are less convenient for separating a half-portion. Market Basket is cheaper for the jumbos (around $4.60-$4.90 for 26/30s) and jumbo through colossal are pretty good there, but the smaller ones are not great. I wouldn't make it a destination just to buy shrimp, but if you are going for something else its a good place to stock up.
Also its been so long that I have been there during the workday, that I forgot they serve lunches to go. They had fish and chips, plus a number of specials (tips and so on), for around $7. As far as other things of note: they had 4.99 sirloin strips, .99 picnic, two types of boneless thin cut beef ribs and short ribs for 2.99, specials on sirloin/steak tips, and ground beef for $1.49. I also like their selection of liver and its less expensive there. The had added freezer capacity and had a bunch of frozen rabbit and plenty of produce.