OK, this is a little convoluted, but Happy Fathers Day here is how it works (hat tip to TPG) but here's some documentation on a promotion that ended June 16, keep on the look out for more, but the basic idea is you find a retailer that is on both the United Portal and also where you can buy an egift card on their mobile application:
- Buy through the mileage plus shopping portal for 15x the normal rate. Note that you can use any form of payment to do this, just click through the portal. That's basically 30% off right from the start through June 16
- If you spend $150 then you get an additional 500 miles (so 3x multiplier, an additional 6%) through June 23.
- If you use the Mileage Plus X application then you can buy a Nike gift card for 10x off and use this for the above purchase.
- If you have a United credit card, then this purchase above is multiplied by 10% more.
So doing all the math, this promotion is 15x + 3x + (10x *1.1) = 28x and at 1.7 cents value thats an amazing 47% off.