You probably know http://bighugelabs.com/flickr/billboard.php .
It should be fairly easy to create billboards like this with GIMP.
Bottom layer: an arbitrary background.
Top layer: the billboard itself, with empty (transparent) contents.
Then the billboard image, cropped to the right size, can be inserted
between these layers and voila!
The crucial part is the image of the billboard.
Has anyone already done this, and wants to share?
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