I've always felt the game (not just mages) should apply a global change to crit, whereby if your crit chance goes over 100% for any ability, you do increased damage based on the amount over 100% you are. Say for Ice Lance, if you go 10% over 100% chance to crit on FoF, your Ice Lances now do an extra 10% damage. Or a Death Knight using Obliterate on a KM proc while he has 10% crit chance, would now do 10% more damage on that ability.
I think Chaos Bolt works this way, as it is always a guaranteed crit. Would help fix crit scaling on a lot of classes (Mages, Warriors, Ele, DK, Hunters), but would need a little tweaking.