A you're the man now, dog! is a phrase used to describe a webpage that consists of a picture with looping sound. One can find many you're the man now, dog!s at www.ytmnd.com. The site is run by Max Goldberg, who I believe lives somewhere in the New York City area, based off a PO box address. The original you're the man now dog! was created by Max and can still be seen at www.yourethemannowdog.com. It consists of a picture of Sean Connery tiled across the page with the line "You're the man now, dog!" cut out of Finding Forrester repeating in the background. Large letters also pop out in the middle of the page that read: "YOURE [sic] THE MAN NOW DOG.COM".
There are many varieties of YTMNDs, but all consist of at least a picture and a looping sound. Often the picture is an animated .gif. Also, almost all have the pictured tiled across the page. Many YTMNDs also have large text that pop out from the middle.
Most YTMNDs relate to some sort of fad in the community. Recently, the fad was to spoil the sixth Harry Potter book. Fads are often recycled; when a new fad comes about it is popular to combine it with an old fad. Therefore, it would be quite easy to find a YTMND of Sean Connery spoiling Harry Potter. One can obtain a more thorough list of fads from www.wikipedia.org. Also, please be aware that much of the "content" of www.ytmnd.com is rather... adult. But then again, you're at E2, so chances are you don't care. Sites with loud expletives and nudity are often moved to www.ytmnsfw.com, though.
Thanks to www.wikipedia.org and the www.ytmnd.com forums for their information. I don't recommend browsing said forums unless you're a masochist.