for controlling its probably best go for ice/dark.
From ice blast you get 2 single target holds in freeze ray and bitter freeze ray. Then there is also the slow secondary effect of the blasts.
From dark miasma you've got tar patch to add to the slow effect and also increase your dmg. Useful for things like blizzard etc aswell to slow down the scattering. Howling twilight can be used as a disorient aswell as a rez. Fearsome stare is a fantastic power and will add to your mob control. Then you get petrifying gaze aswell which is another single target hold. Your dark servant also gets this so really you can have up to 4 single target holds with ice/dark aswell as fears, slows and disorients.
Edit: Other than /dark /rad may also be an option. You have you debuff powers to reduce mob speed, resistance etc. And then 2 AoE holds in choking cloud and EMP Pulse.
Yeah, Ice/Dark is the way forward here. I've got one at about 34 or something like that. You can have 3 single target holds, fear cone (totally awesome!) and something else controllery from the dark set. The area intangiability thing?
The great thing is, you can make it a high damage build too
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
[ QUOTE ]
The area intangiability thing?
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[sarcasm]Oh yes the wonderful Black Hole, how could we forget about that[/sarcasm] 
Dark does seem the best secondary, but what about the dark imobalize cone(tenabracios tentacles?) would that not be more useful then a single target hold(yes i know the difference between hold and imobalize) or am i compleatly mistaken?
Ice / Dark is certainly the villainous Flavour of the month.
But a DDC (Dark/Dark Corrupter) will give you some AOE control with Dark Pit (its a little bit better than the Defender version I think) and Tentacles. Plus you'll still have the Single Target Hold from Dark Miasma.
Just a suggestion.
Dark rad is pretty viscious; You can floor there accuracy with all the accuracy debuffs and the mighty Radiation infection, Immobalize and disorient them (if you slot dark pit up for accuracy) effectively giving you aranged AOE hold, Do their resistance and damage in with Enerverating (sp?) field, you have two AoE holds as already mentioned and the mighty lingering Rad to slow people to a crawl. You can control huge ammounts of enemies with this set: In theory, you could slap tentacles and dark pit on one group, with RI, EF and LR on another, and stand in the middle of a third with chocking cloud on, spamming cone attacks to drop their accuracy 
It's got lots of oppotunities for offence as well, especially if a teamate of yours dies 
Definetly worth a look... so much so I might just role one!
I agree with ice/dark, with ice you get holds and slow effects, which will really help keep your frail corruptor out of harms way, and with dark miasma you get one of the best heals, kickass debuffs, a AoE fear power, black hole AND dark servant, how could you resist.
Best set would of course be... *drumroll* ...sonic/dark! Sonic gets a cone knockback, a cone sleep, and a single disorient. On par with dark for pure controller, and with significantly better single target damage.
I've noticed a trend recently toward /rad corrupters that don't have Radiation Infection???
To me this is the single most useful power in the whole set (if not the game) and to miss it out is to gimp the entire /rad powerset.
I am wanting to make a new corruptor which has a large emount of controll and would like some advice. From what i can see dark or ice would make the best primary,not too sure about a secondary. So please give me any advice you may have.