Dungeons & Dragons Statistics
This is just a random collection of statistical analysis I've done of Dungeons and Dragons when curious. All statistics are for Third Edition.
Chance of self stabilization
A character whose hit point total has fallen below zero is bleeding. Each round he loses another hit point. If he reaches -10, he dies. Another character can use the Heal skill to try and stablize him or use magical healing. Failing that, a character has a straight 10% chance per round to self stablize.
So, your friend at -3 and you can't really afford to stop fighting the dragon to bandage him. What are his chance of surviving?
Average Weapon Damage
This has grown a bit out of control and is now its own page.
The Monkey House has a bunch of D&D math, including calculating XP requirements as a closed form expression, average hit points using various reroll systems, analysis of flaws in how damage scales up and down with creature size, and a calculator for optimal use of the Power Attack feat.
Kevin Sullivan has a page on D&D statistics, including chances of success on opposed skill checks and a bunch of information on expected attributes given 4d6-drop-low