I was looking for a discount for Dogfart and I came across this site:
http://discounts.freeones.com/
They have some good deals. Up to 70% off of a month of Brazzers or Mofo, etc... The deals change though, sometimes it's 70% off, sometimes 30-40%, so if you want Brazzers for $9.95 and it's currently $14.95, wait a few days the price should eventually go down.
I also somehow(probably when I signed up to x-y or z site) got put on a mailing list from td3x.com. They also send out a lot of emails for discounts, the best of which are $5 for a month of EvilAngel or AnalAcrobats, Jaysin, etc... They also do the 9.95 a month for Brazzers or Naughty America, and occasionally a gay site or two.
I somehow got Throated.com for less than $60 for a full year membership. I think I clicked the $5 a month, but when I looked at the other options the full year said under $60 so I clicked on it and the price was right.
I don't work for the site, not affiliated with them in any way, I just only seen one other link in another post regarding discounts and you can find some great deals there. I also signed up to PornPros for the $9.95 and when I went to cancel, they offered me $7.95 recurring membership so I jumped on that.
And yes, remember to cancel your membership THE NEXT DAY. I got hit with a $40 charge from EvilAngel, and of course they wouldn't cancel it....never again will I make that mistake.