It appears that most olders of the US Bank Flexperks Travel Rewards card have now received offers for 3,500 Flexpoints after spending $50 at Neiman Marcus between May 6 and May 19 (the blogosphere has lit up with this offer, for example here, here, and here).
The powerplay here, if you hold the Flexperks Travel Rewards card, is obviously not to buy $50+ worth of junk you don't need from Neiman Marcus, but rather to buy a $50 gift card, and then esell it for as much as possible through a gift card merchant.
I can now report that Plastic Jungle (which offers an additional 1% cash back when you click through TopCashBack), accepts the "virtual" gift cards sold through neimanmarcus.com, and pays 85% of the value of the card in cash. Plastic Jungle verifies card values instantly and sends payments by check or via PayPal.
Since I hold 2 Flexperks Travel Rewards cards, I was able to pay $15 for 7,000 FlexPoints, which are worth up to $140 when redeemed at their maximum value.