I recognize that the use of Warhammer model parts in creating custom minifigures is not a new concept; however, it seems the frequency of their use is increasing...and that's a very good thing.
Take Geoshift for example. He plans on having a series of minifigures inspired by Warhammer, and so far that series has been fantastic. The shield is the real centerpiece here and amazing through and through.
If you would like to learn more about the world of Warhammer, I recommend you start at the Games Workshop website. Although familiar with table top gaming, I have to admit I'm a bit of a neophyte when it comes to this type of wargaming and their use of detailed minitures. I'm hoping over time to become more familiar to help others find the best ways to scout and buy these parts for customization.
Check out more of Geoshift's creations, past and present, on his Flickr stream.