PayPal sent out a by invitation only deal to receive $20 cash back when you spend $50 at Wal-mart.com (and you use your PayPal account to pay). Be sure to check your email to see if you were sent this great deal!
If you don't have a PayPal account, you may want to consider getting one. Other offers I've received this month include 15% cash back on $100 from Overstock.com, $20 cash back on $125 from American Eagle, $10 cash back on $50 from Toys R Us.
These are cash back deals, so you can combine the sale prices from the websites, use a coupon, earn MyPoint or Ebates, etc. PLUS get money back from PayPal!