New Discover card members can get $150 cashback bonus when you make $799 in purchases in your first 3 months.Promotion link
Note, on the promo page it states "limited to the first 1,000 approved applicants".
Also note, Discover has started to enforce one-card-at-time policy in which you can only qualify for one Discover credit card at a time
There's also 5% cashback bonus on up to $800 in purchases for travel and restaurants that lasts through March. There's also a special cashback bonus for March in purchases for grocery and drug stores (up to $200 in purchases).
Credit for this find goes to this FW thread