Resistance, level 0 spell. Can be made permanent. Nightshield spell, cover (for Ref), some alchemical and/or augmented substancies (for Fort and/or Will). Many of those can be found on scenario specific books.
Iron Will, Improved Reflexes and/or Greater Fortitude feats, and many other number of regional/background feats, specially Forgotten Realms ones.
Some classes, like paladin, add Wis, Int or Cha to your saves. Some feats do too, but they are very rare and hard to find. Familiars for spellcasters, magic itens like cloacks and other things.