Some good spice dictionaries include a list of spices and their uses from EZHealthyWay.com and the herb and spice dictionary from Recipe 4 Living. The guide from EZHEalthyWay.com includes pictures, while the dictionary from Recipe 4 Living provides recipe samples.
The EZHealthyWay.com dictionary covers spices from allspice to turmeric. Included with each spice is a description of its color, what it smells like and its most common uses in food. At Recipe 4 Living, the dictionary lists spices in alphabetical order, gives a brief description, and then lists a couple of recipes using that spice. For example, a recipe using allspice is pickled chipotle chilis, while a recipe that uses caraway is black Russian bread.