For those of you trying to integrate django-storages with Amazon S3, don't select Frankfurt as the bucket region. Use the default region (US standard or something). You'll get into weird HTTP 400 errors otherwise.
Also, make sure that DEFAULT_FILE_STORAGE is 'storages.backends.s3boto.S3BotoStorage' The other engine mentioned, 'storages.backends.s3.S3Storage', is broken.
In addition, add AWS_QUERYSTRING_AUTH = False
to your settings.
Otherwise, django-storages breaks browser caching by default.
SO Answer: http://stackoverflow.com/questions/15668443/django-storage-with-s3-boto-break-browser-cache/15710661#15710661