I've known about lignonberries for a long time, but, knowing they were Scandinavian, it never occurred to me to look for them in a local grocery store. Turns out Harris-Teeter has them and at least one other (possibly Kroeger).
They're commonly made into jam or preserves (and the preserves are often used as a sauce, for example, on pancakes). They also go well with roast meat. If you like cranberries, you'll love these. If you don't like cranberries, you might find these more palatable so if anyone ever offers you any, give them a try.
These go a long way in redeeming Sweden for foisting lutefisk on the world.
ERA: I threw an extra "n" into ligonberries. I corrected it in the subject line, but I know I won't find all instances in the text so I left that alone.