The Kill Teams of 40k back in 4^th edition were fun little skirmishes that added a neat dimension to the game.  They allowed a player to have a small little army that, while almost certainly not legal in a normal game, were fun to paint and collect.  It was far more conducive to personalizing a model (such as giving him trophies, painting him differently than the rest of an army, etc) and made the game seem just a little more personal as it is easier to project yourself onto one or two models rather than a whole army.  Read more... (1308 words, estimated 5:14 mins reading time)