Increasing Aura size

[Morph Bark]

Are there ways of increasing the range of the aura of a marshal or dragon shaman or similar auras? Bards have the alp horn to help them boost the range of their "aura" (aka bardic music) and I recall once seeing mention of a way to boost the range of marshal/DS auras as well.

[Cog]

From Fiendish Codex II, there's the Dilate Aura feat.

[Vortling]

Dragon Shamans have the Dragon Spirit Amulet from MiC. It doubles the range of their aura a few times per day.