Ways to ignore SR off the top of my head:
1) Dweomerkeeper (duh)
2) Warlock with Supernatural Transformation
3) Get the spell as SLA, then Supernatural Transformation
4) Use spells with SR: no (duh)
5) The enchantment/illusion specific base caster class whose name I forget.
6) Eldritch Theurge combining a spell with vitriolic blast-makes the spell ignore SR and deal acid damage. Then use mastery of elements to turn it to sonic.
7) Use cursed magic items that don't allow SR even when the original spell does.