I've only really looked at the non-sanctified Sorc/Wiz spells, but I'll mention some of the better ones (in my opinion). I wouldn't necessarily call many of these "overpowered," but certainly good spells
Yoke of Mercy - For just a 2nd level spell, it can be used on things 4 HD higher than the caster, and causes the target to fight mercifully. If affected, the target only deals non-lethal damage, avoids using damaging spells & spell-like abilities, and does not deliver a Coup de Grace, etc. There is an abstinence component present that restricts abuse, but it could still be an awesome spell for casters who predominantly use non-damaging spells, especially a sorcerer with heighten spell (to raise that DC).
Elation - Large burst area giving
morale bonuses to str, dex, and movement for all party members; moderate bonuses yes, but they will rarely have stacking problems and should affect the caster's entire party. At spell level sorc/wiz 3, and bard 2, this one's a keeper.
Radiant Fog - Level 4 - Seems like it could be extremely effective as a defense measure for a caster. Havn't playtested this, so not entirely sure.
Emerald Burst - Level 5 - It has a 1000 gp component, but if you can afford that, this is a great spell for any do-gooder to have. Fireball spread, stuns evil creatures for 1d4 rounds. Area stun, yum!
Star-Mantle - Level 6 - I actually originally posted this in the overpowered/underpowered thread asking what folks thought. Eldren has already mentioned it here, but it's a pretty badass spell (particularly when combined with DR and/or a Fire Shield/Radiant Shield/similar effect).
Quickshift - Level 6 - is another one that Eldren has mentioned. Definitely makes the list for sorcerers, methinks.
Edit: I think I may have missed a Celestial component on this; shortly after making the post I loaned my BEoD to a friend, so can't confirm it.
Wages of Sin - Level 6 - Wowsers!! This could change a large battle drastically! It has a medium range, and affects as many evil targets in that range as the caster has levels. Everything that fails it's save:
believes that its allies are trying to kill it & attacks the nearest Evil creature to the best of its ability. Targets do not ignore other threats, but attack other Evil creatures in preference to other foes. Who is likely to know your foe's weaknesses better than his comrades, henchmen or minions? Simply amazing. The abstinence component on this one seems a little trivial to me, *shrug*. Cast it on raiding/hunting party (or even a tribe!) of hill/frost/fire giants and watch them beat each other to a pulp. Weee!
Amber Sarcophagus - Level 7 - Very similar to forcecage, except it a) requires SR check, b) Causes the contained creature to go into stasis, c) can't be dismissed by the caster at will and must be busted open, d) lasts days/level rather than hours, and e) has 1/3 the material component cost (500 gp). In a lot of situations, features of this spell would be preferable to a forcecage.
Eladrin Form - Level 7 - like radiant fog, I havn't playtested this one, but it looks like it has some serious potential.
Since my sorcerer character is only 15th level, I havn't needed to read/try the level 8 or 9 spells in depth yet, so won't comment on any of those.