Beating Dragon's Fort Saves?

[Vaz]

Is there any way to lower a Dragon's Fortitude Save without requiring a Fortitude Save of its own to do so?

[JeminiZero]

Hit it with no save debuffs. Like Enervation (http://www.d20srd.org/srd/spells/enervation.htm). Sickened lowers Saving Throws by -2, so no-save sicken debuffs like Stolen Breath (SpC) can also work.

Both of these however, requite you to get through the SR.

[Ithandor]

Depending on level, Limited Wish can be used to apply a -7 to saves, with no save. SR applies though, but Assay Resistance or True Casting can be used to help overcome that.

[Ravens_cry]

Bestow Curse will help, though you probably want some way of doing it from a distance as its a touch spell.

[Person_Man]

Doomspeak (http://www.wizards.com/default.asp?x=dnd/iw/20050505b&page=4). Burn a Bardic Music use. Target gets a Will Save vs. 10 + your character level + Cha bonus, or they take a -10 penalty on attack rolls, saves, ability checks, and skill checks for 1 round.

Note the ridiculous Save DC. (Character level, not 1/2 character level or 1/2 your Bard level). It was probably a misprint, but it was never errata'd.