Photobucket has a lot of them. You can also surf this link: http://mubi.com/topics/2132. In the link somwhere are the parameters of a Criterion cover, so anyone here good with photoshop can take a stab at this.
#4
Baerdog
I love this one from that thread you linked.
Edit: This one too.
#5
The Lovely Boehner
I like the ones for terrible movies that would never get a Criterion release more.
Like the SA ones above? Terrible was maybe the wrong word, I have nothing against Dodgeball, it's fine, but just movies that are far removed from what Criterion usually goes for.