1. Lemon Juice - good in almost any non-creamy soup,
especially chicken soup and bean soup.
Balsamic Vinegar- just a few drops can add amazing
depth.
Wine- red or white depending on your soup.
WorchestershireSauce(moelleux aux noix)
Tomato paste - a tablespoon or so of tomato paste can
balance saltiness and create more interesting flavor. Of
course, the old standby for oversalting is potatoes.
Cognac or brandy
Honey
Cinnamon - try in spicy soups and tomato soups.
Nutmeg - good in creamy soups, but in tomato-based
soups.
Boullion cube - if the soup is just a bit weak, this is not a
gourmet ingredient, but it might do the trick.
A few chopped anchovies - chop them up well; your
soup won't taste fishy.