Here's some additional information (of a variety of ages):
http://yabb.jriver.com/interact/index.php?topic=86216.0http://yabb.jriver.com/interact/index.php?topic=39459.10http://yabb.jriver.com/interact/index.php?topic=51551.0A bunch of this is quite old (and improvements have been made since then), but it should give you some ideas.
I've posted about my uses here quite a bit. MC is not, a "DJ-ing" application, like Traktor, or a DAW like Ableton Live or Pro Tools. However, it can be useful even alongside these applications for a variety of uses including sound-shaping and just media management. If you're "live mixing" like a Mashup Artist, then MC won't meet your needs (alone) for this task.
However, it can be VERY competent for a variety of "traditional" DJ situations (playing music at a Wedding, parties, clubs, or whatever). If you'd be using just two separate zone outputs to live (or maybe three, with a third for your headphones), and crossfading between them with a physical mixer, then you'll find a lot of what you need built into MC.
Zones are the key.