I've heard that even though cinnamon is widely used in several types of sweet food-products, it's actually not a sweet spice.  Is is true? If yes, why is it used in sweet food-products? Either way, which non-sweet foods use it? 
Cinnamon itself is the bark of a particular tree, and is not terribly sweet in any objective sense.  I cannot think of a single spice that is in itself sweet.  Spices are generally aromatic, pungent, or hot, but not sweet.  Even vanilla is in fact fairly bitter on its own, as is chocolate before sugar is added.  Cinnamon is a warm spice that many cultures feel compliment many sweet dishes, and many people find it a pleasant taste so it is widely used.  There is no reasonable way to give an enumeration of non-sweet foods that use it.  While in Western European derived cultures, its use in savory dishes is fairly unusual, there is a large tradition of using it in savory dishes in South America, India and Pakistan, the Middle East, North Africa and so on.  One example in North America would be Cincinnati style chili, which is characterize by its sweet spices, often including cinchona and chocolate. 