An example of proxying a Tumblr blog as a subdirectory in nginx (w/o regexs)

tumblrproxy

server {
  # ...

  location / {
    proxy_set_header Accept-Encoding '';
    proxy_pass http://<NAME>.tumblr.com/;
    sub_filter http://<NAME>.tumblr.com/post /post;
    sub_filter_once off;
  }

  location /post {
    proxy_set_header Accept-Encoding '';
    proxy_pass http://<NAME>.tumblr.com/post;
    sub_filter http://<NAME>.tumblr.com/post /post;
    sub_filter_once off;
  }

  # ...
}