On the note of reduced HP, a friend of mine came up with the following system that gets dirty quickly, but isn't insane.
Basically, you get your first hit die from your class. It's maxed out, as normal, but every level thereafter, you only add your Con bonus. However, your HP maxes out at 30.
Not only does this make HP much more precious, it also make Toughness a useful feat.
I added a twist, in that taking Toughness increases your HP and your Max HP, meaning you could have up to 33 HP, to a maximum of 45.
I like the system, and have used it in many a game. I plan to continue using it, too, simply for that moment of...
Fighter:
"I'll just rush through the wall of flame and take the AoO from the bugbear! I can take the dam... oh, damn."