Now, you are not to share this with anyone. Go to Mike and Patty's - 12 Church St - for breakfast / lunch. OUT OF THIS WORLD!!
Ditto on the Duck Boat tour, and Fenway Park tour. I'm not sure what day it runs, but Copley Square has a great farmers market.
Some great shops / eating establishments on Newbury St. The independance tour is pretty good and if you are really good at blending in you might be able to get in without paying. Wink wink.
I went around and checked out old fire stations when wifey was shopping one morning. Met some great folks and got some great pictures of the buildings.
DANG almost forgot. Sam Adams and Harpoon breweries have tours and tastings.