Improving an existing Breath Weapon for a True Dragon, without feats

[ViperMagnum357]

I am looking for any and all 3.5 material, either first party or licensed, that improves an extant breath weapon; I already have a handle on the feats available, so now I am looking for magic items, grafts, templates, and PRCs. I think I can work the Ravening Psychosis, Dragon Ravager PRC and possibly the Dragonspawn Abomination template into the build; that adds four dice to the damage, +2 the save DC and reduces the cooldown to 1d3 rounds between three rounds of use. One of the ArchDragon templates will add a rider effect, as well. So, what should I look at next?

[Biffoniacus_Furiou]

There are spells in Draconimicon, most of which was updated in Spell Compendium. Those add a carrier effect to the breath attack, depending on the spell. Blinding Breath is probably the best one.

[pabelfly]

Dragon Spirit Cincture

[MisterKaws]

Animate Breath is nice for minionmancy. There's also the Xorvintaal Dragon template which lets you overcharge the breath effect. Removes spellcasting tho.

[Thurbane]

Horribly sub-optimal, but Dragon Samurai (http://archive.wizards.com/default.asp?x=dnd/ex/20030906c) gives you a one/day breath weapon that explicitly stacks with an existing breath weapon of the same energy type.

If it weren't 1/day, it might be interesting, but as it is...terrible.