It depends on the type of cleric you are.
For a front line bruiser cleric:
-Martial Weapon Proficiency: Greatsword, Greataxe, Longsword, Battle-axe, Warhammer, Glaive, Ranseur, Guisarme (Free with War domain--otherwise only worthwhile at 1st level; at higher levels go for an exotic weapon (+1 BAB means you can't at first level). The benefit is that you get one more caster level than you'd have if you multiclassed to fighter or paladin). This feat is best for clerics who want to wield two handed weapons--the difference between the longsword/battle axe/warhammer and a heavy mace or morning star is only crit range or multiplier. The difference between a greatsword and a shortspear is much more dramatic.
-Weapon Focus: (also free with war domain) Your weapon of choice--morning star and heavy mace are the outstanding simple weapons.
-Power Attack
-Cleave
-Sunder
-Improved Sunder
-Improved Critical
-Power Critical (if you have a weapon with a x3 or x4 crit multiplier)
-Divine Might (if you have Charisma 16+)
-Extend Spell
-Persistent Spell (T&B). Good for Divine Favor and at high levels Divine Power.
For the spellcasting focussed cleric:
-Spell Focus (Enchantment or Evocation). Enchantment is good at low levels for Random Action, Calm Emotions, Hold Person, Command. Evocation is good for Sound Burst, Holy/etc Smite, Flame Strike, Firestorm, etc.
-Greater Spell Focus
-Spell Penetration
-Greater Spell Penetration
-Empower Spell (This is also good for melee clerics--use it to empower your Bull's Strengths and Endurances).
For an archer cleric:
-Martial Weapon: Composite Longbow (free for elves, may be free with War domain for certain deities--Phaulkon (Living Greyhawk Gazetteer), Solonor Thelandira (Living Greyhawk Gazetteer, FRCS), Shevarash (FRCS Web Enhancement), possibly Ehlonna or Correllon Larethian if your DM is kind--also check to see if the flexible (longbow=composite longbow) weapon proficiency/focus applies in your campaign)
-Weapon Focus: composite longbow (See above comments on war domain and flexible weapon focus).
-Point Blank Shot (Free with Elf Domain (FRCS))
-Rapid Shot
-Precise Shot
-Manyshot (ELH-- IMO, your DM's nuts if he allows this but it is good)
-Zen Archery (Sword and Fist--most useful for human clerics or any clerics with low dex)
-Improved Critical: Composite Longbow
-Extend Spell
-Persistent Spell (T&B)
For all Clerics:
-Extra Turning (if you've got lots of undead in your world)
-Divine Vigor (if you need to move quickly in your fullplate)
-Scribe Scroll
-Craft Wondrous Item
-Craft Magic Arms and Armor
-Chain Spell (GMW for all of everyone's weapons--too bad it's so high level)
-Lightning Reflexes
-Iron Will (if you're not making the saves on a roll of 2 already, this helps--the better your save is, the more difference it makes)
-Great Fortitude (if you're not making the saves on a roll of 2 already, this helps--the better your save is, the more difference it makes)