I am going to say 'no' to 'real' armies like we have in the world today because, simply, there aren't enough wizards around to really make a large, standing army. Voldemort's followers really *aren't* an army, per say. They probably started off as a band of 'out law' type people following their cult-like leader. Then, as Voldemort's following grew, they progressed into a larger group of people. Among that larger group, there is varying levels of dedication, class, and ability. Voldemort seems to pick his 'inner circle' through these criteria, but there are no special rank names given outside of the term 'Death Eater' and the Dark Mark.
Do we have them? Because Voldemort's seemed pretty chaotic, if you ask me. Is there any references to wizards actually making armies like the US and British ones? And if they did, would they be Ministry/Government commanded?