All clerics in a RAW game can either Turn Undead or Rebuke Undead. This doesn’t seem right to me because it seems to me that not all settings or religions would put enough emphasis on undead to make it relevant. Also, I don’t really like the way turning works — it either doesn’t work at all (the undead is too powerful and the cleric can’t affect it, or you rarely find undead) or it works very well (you find undead fairly often and the targeted undead are either turned or destroyed).
Either way, I want something better.
In my campaign, all clerics and paladins lose the class ability to Turn Undead or Rebuke Undead. Instead, they get the ability to channel divine power a number of times per day equal to base Will save + Charisma modifier. This ability does little on its own, it is mostly used to power divine powers. Divine powers are gained as domain powers or by taking feats.
A character can also gain the ability to channel, as a cleric, by taking the Channel Divine Power feat. The character need not choose a specific god, but may only take a Domain Feat if he has a patron god that grants access to the relevant domain.