The shifting alliances of Risk are the best part. Like when you ally with another player to take on a stronger player...do you leave your borders relatively unguarded in order to pull more troops to the front against your common enemy, or do you fear your "ally" might stab you in the back as soon as he has the chance? Those are the decisions that make the game what it is.
Or the fact that your ally is really the player you have to destroy...all those schemes.
Risk is glorious. What about the times everyone bundles their strength against one player who looks to be winning the game? That's great fun. Just like in reality, it's often best not to draw too much attention on yourself in Risk, by desperately going for the whole of Asia for example.
Lay off Asia btw - it's undefendable. Europe sucks too. Best bets are Oz, S- and N-America. Africa is a knife that cuts on both sides.
Heh...Risk online sounds ok, but it's no substitution for the real-life deals and negotiating that take place. Much like the negotatiating round in monopoly (which is great fun), but risk is non-stop.