As far as spells that deserve more attention...
Manyjaws - 3rd level SpC: This spell should be the bread and butter of most casters. It does force damage, which is pretty difficult to resist (unless you are facing a force dragon or the enemy happens to know forceward), it lasts for 3 rounds, can select multiple targets, and is easily metamagiked. This should be the spell you use when you aren't necessarily facing something life-threatening, or as an opening spell. Its really good for conserving attack spells.
Veil of Undeath - 8th level SpC: Probably one of the best defensive spells in the game. It gives you a shit load of immunities, including mind-affecting (so there's mostly no need for a mind blank). Basically, this spell makes it so you hardly, if ever, have to make a Fort or Will save; which just leaves Ref (which are usually tied to damage dealing effects anyway, so as long as you have a way to prevent damage you don't need to worry).
*Additionally, when combined with Shapechange into something with Regeneration you gain complete immunity to damage from anything except what they aren't resistant to. You could do a troll and then cast energy immunity fire and acid for complete immunity to all damage. You don't even need to persist to do this. Just
use a greater metamagic extend rod on both Shapechange and Veil of Undeath, leave 3 slots open for them, and cast Energy Immunity twice (since its 24 hour duration).
Eyes of the Oracle - 6th level DM: One of the biggest overlooked spells IMHO. It allows you to ready a standard action every round. As far as defensive purposes go, this spell is golden. What happens when you use up your immediate action and contingency? With this spell you can surprise enemy spellcasters that think they have you locked down. It has other uses as well, but for me, having a bit of extra defense is always a plus.
Effulgent Epuration - 9th level SpC: It gives you one orb per CL which you can use to selectively negate one targeted spell on you, each. Normally I don't even use this spell (mostly because of Rods of Absorbtion), but its still a nice defensive spell that I never hear mentioned (probably because of RoAs).
Oh yeah, and Anti-Life Shell...It never specifies but does the caster have to be non-living to cast it around himself? Otherwise, its a pretty good spell for preventing melee combat, assuming they don't have reach.