Do you have craft wonderous item? Making/buying some cloaks of resistance would be a nice move... and if you have the feat- making the item for another body slot becomes a possibility. Gloves of dex, periapt of wisdom, and amulet of health also become options.
Obviously, theres lightning reflexes, iron will, and great fortitude. If you have a decent charisma score... complete adventurer (IIRC) has a feat that lets you use charisma instead of will for reflex saves.
Let's see... I wouldn't worry about will too much- people know wizards have high will saves, and probably won't target you with such attacks. Minor globe of invulnerability will help you to avoid needing to make the saves as often- and that may be the best track to take... avoid being in a position where you need to make saves. Stay to the back (or middle) or the party, maybe enough back to avoid Area effects... stay invisible when possible to avoid being targetted by rays... etc.
That's all that comes to mind off the top of my head.
Vorp
PS/Edit: Look into various prestige classes- not all of them start out with a boost to will... the planeshifter in manual of the planes, and the mindbender (i think) in complete arcane give boosts to fortitude right off the bat. Even if you take a one level dip in it, you gain a +2 to SOME save, and usually some other nice ability.