The Dragonmount.com team have Tweeted a picture from JordanCon of the tentative US cover art for Towers of Midnight, the thirteenth and penultimate novel in the Wheel of Time series, due for publication late this year. At a guess, the three characters on the cover are Mat Cauthon, Thom Merrilin and Noal Charin.
Okay, not actually that helpful, but it does appear to be superior to The Gathering Storm's depiction of Rand al'Thor having some kind of epileptic fit in front of the Addams Family house, even though it appears that Sweet is trading even more on past glories (this is no less than his twenty-first piece of cover art for the series by my count). This cover evokes his work on the Wheel of Time roleplaying game for Wizards of the Coast:
Based on this, I expect the full cover art to be released soon, hopefully followed by Orbit's UK artwork.
Update: More recent Tweets indicate that the cover art may actually be a different painting (although we heard this before for The Gathering Storm and they pretty much used what was in the rough sketches, just turning Rand around 180 degrees) altogether.
Update: a clearer image courtesy of Dragonmount: