I have decided that the in depth post I was working on was to in depth for the blog and much better as an academic pub (tho I may excerpt it here at a later date). As such, I have gone ahead and archived the anti-obama posters in a permanent page accessible through the link of the same name at the top of the page. The photos are arranged by written or symbolic message/meaning. The archive will be updated as more images become available. All images are cited where the information was available and should be cited if you use them elsewhere.
If you are collecting images, there are also several archives on flickr with which to start. Mine are here.