Well Technically there are 3 Human (or mostly) armies, Empire, Bretonnia and Warriors of Chaos.
There are 2 abandoned armies, Dogs of War and Kislev.
Now you can use rules from other armies for Cathay, Ind, Araby, Nippon, Etc. I've seen Nippon army using Bretonnia's book for example.
There are a few fan-books out there for human armies, Pirates of Sartosa, Araby, Norse and others to use for fun games.