Today Ebates has a daily double promotion for 51% cash back at Magazines.com
Magazines.com has some pretty good prices to begin with and getting 51% cash back on top is a good deal.
I recently bought my wife a subscription of the Oprah magazine as a present and I paid a fairly good sale price of $13 on Amazon. Now its $18. Magazines also has it for $18. With the 51% cash back that would make the net cost only about $9. So some deals there are pretty good.
But be sure to shop around. I have a subscription of Businessweek for $20 / year. Magazines.com price is $50 and even with 51% cash back thats still about $5 more than I'm paying.
One detail to be aware of, I think by default that Magazines.com signs you up for automatic renewal of your subscriptions.