Chase is offering up to 45,000 bonus award miles as a new United MileagePlus Explorer cardmember. You receive 30k after you spend $1000 in the first 3 months, 5k for adding an authorized user and 10k for $25,000 spent in the first year. $0 intro annual fee for the first year, then $95.
sign up online and get 30,000 bonus points, sign up in the store and get 50,000 bonus points.