i guess this is not a question with an immediately obvious answer. For the vast majority of us, resists other than corruption have not been something to think about for many many years. The developers capped resists (on a per level basis) a long time ago, and then added in a few ways to raise those caps, i believe: Finishing the Muramite Proving Grounds trials, certain heroics achievements, finishing the Dragons of Norrath progression. Usually these special achievements and rewards are tied to finishing most or all of the progression of a given expansion. At any rate, past a certain level range - 60s maybe, if you have any reasonable amount of current content gear, your resists will all be capped all the time(except for corruption). Having over cap resists does not effect much, unless something actively lowers your resists. So to answer your question- i don't think so? And if it does, it probably won't make a difference as the developers like sticking the unresistable tag on things they mean to stick to you- usually the worst debuffs. If i were to guess- perhaps some bard songs raise the cap? Maybe a mage buff or two vs fire?
Annastasya has summarized a great answer, but for posterity there are a number of ways to increase your survivability vs spell damage. http://www.raidloot.com/Spells.aspx?effect=Block Next Spell&view=Table http://www.raidloot.com/Spells.aspx?effect=Increase Chance to Resist Spell&view=Table http://www.raidloot.com/Spells.aspx?effect=Absorb Spell Damage&view=Table http://www.raidloot.com/Spells.aspx?effect=Absorb DoT Damage&view=Table http://www.raidloot.com/Spells.aspx?effect=Increase Chance to Reflect Spell&view=Table I don't know of a good resource that summarizes special items (ex: Jann's Illusion, Skull of Null, Diplomatic Immunity) that are readily available and confer the above buffs.
Was really just hoping there was a magic buff out there that would allow you to go past the cap in magic resist so I could resist mezz a little more. I couldn't find one and was hoping I had missed it. Doesn't sound like there is though.
