Shrimp/Lobster stock might sound unappealing to some people, but it's very good. One of my favorite ways to use it is to mix it with tomato soup, add a splash of half & half and in minutes you've got bisque!
Just like regular stock, it's easy to make. Whenever we have lobster, or those delicious sweet shrimp, I save the shells in a ziplock and throw them into the freezer until I have enough to fill a large sauce pan. I fill with water, add a sliced lemon, some thyme and parsley (you can use dried) and a bay leaf. Pinch of salt. After it comes to a boil, I reduce the heat and let it simmer for about an hour, then I turn up the heat, add 1.5 cups of white wine and boil it until reduced to about half. Then I strain it, let it cool and refreeze in ziplock bags and it's ready to go for whenever I need fresh stock. If you wanted it more concentrated (more flavor, less water) just let it slowly boil down and reduce to your desired preference.