You can get double cash back from several vendors at Ebates.
Some of the double cash back merchants are :
Barnes & Noble = 8%
Dell = 4%
Home Depot = 5%
HP = 5%
JCPenney = 6%
Lands End = 6%
Macy's = 5%
Nordstrom = 5%
Sears = 4%
Staples = 4%
Walmart = 2%