Area of effect AC boosts with minimal casting..

[animewatcha]

Whether it is the classic 5ft adjacent reach with allied defense or 30 foot range sacred ac bonus of protection devotion feat ( right devotion ?). With minimal direct spellcasting ( like only taking cleric for turn undead for devotions ). Not so much including direct penalties to enemies attack rolls, but rather a martial character making use of things like protection devotion and allied defense.\

Items, Prestige classes, feats, etc...

This is for 3.5. Pathfinder, no. Dragon magazine and dragon comp, yes.

[ExLibrisMortis]

I think Marshal, Dragon Shaman, and Divine Mind may have options. There's also Dragon Lord. All of these get auras.

Iron Guard's Glare is probably worth getting, even if it's an attack penalty - it's a pretty solid -4, no save.

[Thurbane]

AFB, but I think there's a feat in MH that allows you to add a shield bonus to AC for adjacent allies. I think the Tactical Soldier PrC (also in MH) may also have similar abilities.

[Waazraath]

I think Marshal, Dragon Shaman, and Divine Mind may have options. There's also Dragon Lord. All of these get auras.

Iron Guard's Glare is probably worth getting, even if it's an attack penalty - it's a pretty solid -4, no save.

You can get the draconic aura's also with a feat, though it needs a race with the dragonborn subtype to be effective.

Saint template and several exalted prestige classes give 'circle of protection evil' as a permanent feature.

[MaxiDuRaritry]

Magic Circle Against [Alignment] does this.

And it's not AoE, exactly, but war weaver allows you to buff multiple people at once with multiple, non-AoE, single-target spells.

There's a banner in Heroes of Battle that grants everyone around you protection from evil. 8,000 gp.