Over 15o comic book retailers participated in an Amazing Spider-Man #666 promotion to have their store featured on the cover of a specially select print run of the comic in question, out next week.
Each retailer had to commit to buying 150% of their normal amount of the normal cover and then at least 500 copies of their special variant version. Which means that's an extra sale of, say, 80,000 on top of the normal figure. Biggest selling comic book of the month, folks, by far.
And this is the first publicly seen copy, from Vintage Phoenix Comic Books of Bloomington, Indiana. They put some out on the shelf after closing to take the photo, but they will only be for sale next Wednesday.
And here's a slightly better look at the cover.