marching order rules - I mentioned these in my session write-up. A snap to use and easily adaptable to D&D.
no Read Magic - One of a priests main skills is linguistics, as all scrolls and spellbooks are written in various ancient and/or foreign tongues. I'm not sure if I would use this one, as I think spells that cannot be read by normal means works well in a Vancian system, but it would be easy to adapt if one so desired.
save for half/2d6 - If a saving throw is allowed for half damage and you make the save then you take half damage or 2d6 damage, whichever is lower. This means fireballs and dragon breath wouldn't be auto-kills for low level characters.
Int and Con give combat adds - Being smart and healthy means you can beat people up better. Being an idiot makes you less efficient at murder. I'm not racing out to adapt these ideas to my D&D games, but I'm intrigued.
Simultaneous Initiative - Here's one I don't like. If you lose initiative you get to strike back even if you are killed earlier in the round. I'm willing to put PCs through all sorts of hell, but I just can't bear the idea of killing them with a monster they already killed.
Secondary skills - Called 'original skills' in the text, everybody starts with 1 to 10 non-adventurers skills. In addition to listing fun stuff like 'alchemist' and 'assassin', you also get a little flavor for the setting by noticing skills like 'slaver' and 'courtesan/Don Juan'.
Fighter class skills - Weapon proficiencies are tiered. Any chump fighter can use a spear, but it takes achieving at least fifth level to learn to fight two-handed with sword and dagger. I'm not sold on weapon proficiencies as a necessary part of D&D, but I like the EPT approach better than AD&D method of just picking any four weapons from a huge list. I've seen chargen with even veteran players slowed to a halt because they were pouring over the weapon charts to pick out proficiencies.
Spellcaster class skills and bonus spells - Priests and magic-users start out knowing a few tricks from a very short list of standard powers. At each level-up they can one more item off the standard list, plus one or more rolls to see if they get random bonus spells. I like this combo approach. I'm always fiddling with the rules for magic-users learning new spells and I may try something like this method.
Spell failure - I really, really like spell fumbles in D&D. But starting out with a 60% chance to fail per casting is really harsh. The chance of failure goes down as you level up and a good Psychic stat can lower the percentage further, but it's still hard on newly minted spellcasters. As an aside, can anyone name a spell that fizzled out on the user in any literature from Homer to Howard? As much as I like spell fumbles, I'm trying to figure out where the heck the idea came from.
Critical hits - A natural twenty is double dice, plus roll again. A 19 or 20 on the follow-up roll is an auto-kill. Simple and effective. Less graphically gruesome than my beloved Arduin crit chart, but still pretty cool.
Wrong target percentages - A Dex score of 40 or lower gives you a 10 or 20% chance if hitting the wrong guy in a fight. Again, I like fumbles but the chances seem pretty mean-spirited. Especially when you're trying to blast some punk with a spell. You have to overcome both spell failure and mis-targeting to get a chance to hurt the baddie.
Two handed weapons - You need a high Strength (80%+) to use them effectively and they do one extra point of damage. Pretty straightforward.
Damage Dice chart - Being high level/having many hit dice gives you extra damage dice against low level/hit dice targets. For example, a 6th level fighter taking on one hit die wusses gets three damage dice per strike, allowing him or her the potential of taking out three foes per round. I'm not sure whether I want another combat matrix in my D&D games, but allowing multiple damage dice for one to-hit roll nicely eliminates those handful of d20's that high level fighters have to throw every round in some versions of D&D.