"American Whiskey" is a catch-all term for any whiskey produced in the US that does not meet the particular criteria for either bourbons or ryes.
This includes whiskeys that have a more even ratio of grains (i.e. not even corn to be a bourbon or enough rye to be called a rye whiskey), that are younger than bourbons, or that have been blended with neutral grain spirit (e.g. Seagrams 7). American whiskeys can run the gamut from light-bodied and easy-mixing to rich and heavy, so there is something for just about every palate in this broad catagory. Spend some time in this section to see what distillers around the country are making and find something new.