My experience with a casting focussed cleric is that strategies differ vastly between 3.0 and 3.5.
In either case, the cleric will focus on wisdom over strength and dexterity. He can afford a lower con but probably doesn't want to. He will probably want a to place a good stat in charisma for turning and intelligence for skills. So, while the combat cleric prioritizes wisdom (slightly more than) strength and constitution and avoids a dex penalty, the casting cleric prioritizes wisdom dramatically more than anything else, values constitution, int and charisma about equally, and can live without dex or strength.
For feats, the 3.0 cleric wanted spell focus and greater spell focus enchantment (Random Action, Calm Emotions, Command, Hold Person, Greater Command, chained hold person), Necromancy (Inflicts, cause fear, slay living, destruction, implosion), or Evocation (Flame Strike, Sound Burst, Blade Barrier, Firestorm, Fire Seeds, etc) the 3.5 casting cleric probably wants necromancy (Blindness/Deafness is added in) or Evocation (if he has an appropriate elemental domain like fire (burning hands, etc), water (cone of cold, ice storm, etc), air (chain lightning), or Sun (Fire Seeds, Flamestrike)). The 3.5 casting cleric might also try to crowd in on the Druid's schtick with Spell Focus: Conjuration and Augment Summoning (best done with a neutral cleric so you can summon everything on the list).
Other feats that are of interest to the casting cleric: craft wondrous item, craft wand, scribe scroll, reach spell, Spell Penetration, Greater Spell Penetration, Improved Initiative, chain spell, Great Fortitude, etc.
Domains: Elemental domains are good (and double by adding elemental turning if you've a good charisma). Alignment domains are surprisingly good with Holy Smite, Blade Barrier, etc leading the way. The magic domain is attractive for item creators and the ability to use fireball or haste (esp in 3.0) off of a scroll. If you use Arcanis domains, the afterlife domain is quite good since Spectral Hand enables you to deliver inflicts at range. Domains like war destruction and strength are still viable (War gets the power word spells and strength gets the Bigby's hand spells) but aren't nearly as attractive as they are for combat clerics.
Equipment: You may still want to wear fullplate (unless your strength means that it would put you at a medium or heavy load) but it's not essential. A chain shirt is fine for most tasks and my Living Arcanis cohort has done just fine in leather armor (with a strength of 8, there's only so much you can carry). You might want to carry a longspear so that you can help out the rest of the party in a pinch and/or can threaten foes while casting your spells. You might also want to have a buckler so you can add to your AC when you're not attacking. You'll want to focus your attention on things like strands of prayer beads, pearls of power, scrolls, periapts of wisdom, phylacteries of faithfulness and undead turning however rather than on getting the meanest magic weapon and the best shield you can afford.
Spells: This will largely depend upon your domains but standouts are:
1. Shield of faith (at mid levels), protection from evil (at low levels), bless, cause fear (at low levels), Random Action (in 3.0).
2. Bull's Strength, etc (in 3.0), Hold Person (in 3.0), Calm Emotions (in 3.0), Spiritual Weapon (in 3.5), Resist Energy (in 3.5), Aid (in 3.5)
3. Magic Circle v. Evil, Summon Monster III, Prayer, Searing Light (at level 6+ and against undead), Blindness/Deafness, Dispel Magic.
4. Freedom of Movement (in 3.5), Death Ward, Holy Smite.
- a multiclassed cleric/wizard... without the power drain.
