non d20 super at RPGnow
http://www.rpgnow.com/default.php?cPath=18&PHPSESSID=8ea8151a93729ed1a8c51864a7fac397
d20 super at RPGnow
Comic Book Super Heroes RPG
http://www.rpgnow.com/product_info.php?products_id=230&
Four-Color to Fantasy
http://www.rpgnow.com/product_info.php?products_id=235&
Vigilance
http://www.rpgnow.com/product_info.php?products_id=146&
Deeds Not Words Revision 1.1
http://www.rpgnow.com/product_info.php?products_id=1685&
d20 in print
Mutant & Mastermind
http://enworld.cyberstreet.com/reviews/index.php?sub=yes&where=currentprod&which=MAMA
Silver Age Sentinel
http://enworld.cyberstreet.com/reviews/index.php?sub=yes&where=currentprod&which=sas9
Godlike
http://enworld.cyberstreet.com/reviews/index.php?sub=yes&where=currentprod&which=godlike
Vigilance also exist in print
Now what I've heard:
Silver Age Sentinel use hit point and classes, it changes the meaning of stats (i.e. the average is around 8-9, and you get bonus die instead of straight bonus) does not use feat, and has a different skill list than D&D or d20 modern (i.e. you have a stealth skill and no awarness skill to counter). Some of those choice are to ensure compatibility with the Tri-Stat version which is considered better by tose who have both. Powers are effect based (you pay for the effect, not a specific power).
Deeds not Word use hit point, class, feat, it's the closest to d20 and has rules for vehicle, a special debt mechanic for extra powerful character, it's considered very good by many.
Godlike is a cool system, the conversion notes are really light (that I know, they are available for free), and you probably won't be able to do marvel character with it.
Hero can do everything, though character creation is a chore (and the system itself is rather slow)
What I know:
Mutant and Mastermind does not use hit point but a damage save mechanic, abilities cap at 20, and and you need power to get above, you select power, not their effect (I've heard that it's as flexible as SaS), It's pretty though the vehicles rules are light.
Four Color to Fantasy is a plug in for D&D or d20 Modern (or Spycraft), you keep the base classes and it add a new class which grant Hero Point with which to buy power from a list, power are effect based (in fantasy, I think that it's the best for a Final Fantasy feel).
Vigilance exist in print
PDF are cheap
I would either recommend to search a bit more info on Mutant and Mastermind or Deeds not Word (or choose wether you prefer a PDF or a print product), I think those 2 are winner when d20 is concerned.