Here's one for the paranoid decaf coffee drinker--D-Caf Test Strips. These tiny strips of paper will tell you if there is too much caffeine in the beverage when you dip one in a small sample. It takes about 30 seconds to display a result and will work with both hot and cold coffee.
Those who get their days ruined by intolerance to caffeine may want to check it out at online shopping site The Spoon Sisters, which sells the product for $9.95 per pack of 20 strips. Or, if we may so suggest, drink something other than coffee.