well
personally i think the issue is what do you think a cleric is?
as written in 3E, IMHO, the cleric is really a secondary fighter with full spell using capability. they dont have the massive flexability of a mage, but they have a much longer life expectancy, can fight up front with a fighter for a short while, and can fight a good magical fight with a wizard.
as they are a full spell caster.. even more so than a sorcerer (i dont like the sorcerer class, but that my biz

).. i find it very hard to understand why they are the only one that has D8 hp and can wear full armor. all other primary spellcasters have fewer hp or cannot wear full armor.
Historically in DnD progression terms, the cleric was given more and more power (like domains) to help make up for the fact that they spent most of their time being forced to memorize healing spells.
1E clerics functioned mostly as a secondary fighter who could cure and do utility/detect type magics. 1e clerics were imagined as fighting holy men. the paladin was imagined as a holy fighter. this held true (for the cleric) because they were restrained from using the full potential of their magic by cure memorization. And since they couldn't really cast attack spells (look at the 1E lists, and when they could it was a opportunity cost decision between damage and healing) they were eventually given (in 2E) special abilities to help people enjoy playing clerics.
during the life of 2E the cleric improvement trend continued, providing cool god granted benefits.. like addtioinal theif levels, some magic user spell casting, removing the weapon restrictions, etc.... all based upon the concept that a god would grant abilities appropriate to their domain. (ie. the war god would be OK with the cleric using a sword) and to continue to provide people with a desire to play a cleric. (a player spent most of his time fighting not as well as a fighter and memorizing mostly cure spells)
3E make a simple, but very dramatic, change to the cleric. Even in 2E with all the special stuff clerics could do they were still limited in their magic use by the fact they had to memorize cure spells. 3E allowed spontaneous casting. It also didn't remove any of the special abilities given to clerics to compensate for their having to memorize cure spells.
I think this is why the cleric is unbalanced. Many (if not most) of the overt damaging at a distance spells were created (in 2E) to make the cleric more interesting to players who didnt just want to play a 2nd rate fighter with healing spells. The concepts of Domains were introduced for the same reasons.
the reason for these additions was the forced memorization of cures, and the removel of the reason for those additions, while maintaining all the benefits leads to the unbalanced 3E cleric.
One final thing about clerics vrs. wizards is a very important fact. A wizard has to learn all his spells. A cleric already knows the ENTIRE list of possible spells (hows that for flexability!). So whenever a DM or Player or Supplement introduces a new spell, every cleric can get that new spell without any of the hassles a wizard has to go through. (alignment issues aside). Clerics dont have the weakness that is a spellbook (ie. you cant steal or destroy a clerics casting ability), they have the advantage of armor (wizards have basically -1 on available magic slots), have almost twice the hp of a wizard, and are the only class to have two completely customizable special abilities.. (domains)
ideas for balancing the cleric.
1. i'd remove almost all overt damaging spells (spells that deal damage at a distance) from a clerics list. that should be the domain of the wizard. clerics can cast negative-buff spells (any spell that gives the opponent minuses.. ie the reverse of the typical buff spell)
2. if your players dont like that, knock the clerics down to D6 hp and take away their domains.
3. if they dont want that. just remove spontaneous casting.
joe b.