The Northern Chocolate company has been a mainstay of the Brewer's Hill neighborhood for some twenty-odd years now. It's a crazy little store- you have to ring a bell to get in, and come prepared for an experience like no other. The chocolate is amazing, though, and worth a little trip. Otter-shaped chocolate is offered in both milk and dark varieties. As you can see, there is a definite otter theme, which only adds to its appeal.
It is The River Otter's tradition to make a stop before Christmas, before Easter, and possibly one or two other "must have delicious dark Northern Chocolate otters ASAP!!" stops annually. On a cravability scale of 1-10, I would place it at about an 8 or a 9.
For a more in-depth article about the place, see this article.