Inspired by an article by John T Sapienza Jr in an old issue of Different Worlds magazine (issue 21, I think), I use the following turn undead tables in my B/X and Labyrinth Lord campaigns. As such, it appears in the upcoming Magical Theorems & Dark Pacts book.
Turning Undead: Clerics have the ability to Turn Undead. The potency of this ability is determined by level. The cleric is able to call upon the name and power of his deity to repel, and even destroy, undead. Turned undead will leave the area by any means they can, and will not attempt to harm or make contact with the cleric. On the Turning Undead table, there will be a dash, a T and a number, a D, or a number or two numbers corresponding to the HD of an undead creature and the level of the cleric. A dash means that the cleric has not attained high enough level to turn the undead type. A “T” means that the cleric automatically turns the undead and the number after the slash is what is needed to be rolled on 2d6 to destroy the undead, and a “D” means that the undead will be destroyed automatically. A number indicates that the player must roll that number or higher on 2d6 in order to turn the undead. When two numbers are indicated, roll once. If the number rolled is higher than the second number, the undead will be destroyed, if the roll is higher than the first number but not the second, then the undead are turned. If this roll is successful, or there is a “T” in the chart, the player rolls 2d6 again and adds half his cleric level to the resul – this is the number of total hit dice of undead creatures turned. A “D” in the chart requires the same roll to determine how many HD of undead are destroyed. No matter what the dice roll result, at least one undead creature will always be turned or destroyed, as appropriate, on a successful turning attempt.
This table actually reduces the power of turning undead for limnal cases (undead of a level roughly equal to that of the cleric), but increases the chance of destroying undead, and also increases the number of undead turned or destroyed for high level clerics (because by the core rules, undead of greater than 6 HD could never have more than one turned or destroyed in a single turn undead check).