Today only, TopCashback is offering double cash back (or better) at a number of popular stores.
As always, it’s a good idea to check Cashbackmonitor to make sure that you’re getting the best rate and to check historical rates at the retailers you’re considering.
From a travel perspective, one potentially notable deal would be 20% back for new customers at Groupon. Check the terms for which types of Groupons are eligible for cash back, but it appears that Groupon Getaways are included. I have never personally booked travel through Groupon Getaways, but 20% back might be useful if you already had a purchase in mind.