Here's something I've been thinking about.
The whole "You topple over and cease to breath" idea, while it works, can be modified to be a lot more colorful. Instead of seeing that message, perhaps a random message from a set of messages/scripts can be chosen.
Ideas... wrote:
-Heart Attack
You clench your chest in pain, as your heart ceases to beat.
You drop to your knees, gasping for breath, and die.
-Stroke
You suddenly fall over, unable to move your entire body.
Your head bursts in pain, and you feel yourself quickly loosing your senses.
-Pneumonia (This one could span over several ticks... perhaps separate each message by a tick or two)
You begin coughing slightly.
You start to cough harder, occasionally spitting out nasty green mucus.
You struggle to continue on your feet, and feel forced to rest somewhere. (At this point in time, you can't move).
You feel yourself becoming more sick as you loose the ability to do anything.
Your coughing becomes painful to the point that you sense death must be near.
Your cough *wtfpwns* you, and you die. (Sorry, just wanted to do that.

)
Rough ideas, I know, but a thought... I'm sure there's more you could do then what I put here. If I come up with more ideas, I'll write them here... I'm just too tired to do it now.