Prerender.io, nginx & meteor; see https://gist.github.com/thoop/8165802 for official gist (non-meteor at the time of writing)

nginx.conf

server {
    listen 80;
    listen [::]:80;
    server_name yourserver.com;

    root /path/to/your/htdocs;

    error_page 404 /404.html
    index index.html;

    location ~ /\. {
        deny all;
    }

    location / {
                try_files $uri @prerender;
    }

    location @prerender {
                set $prerender 0;
                if ($http_user_agent ~* "baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator") {
                        set $prerender 1;
                }
                if ($args ~ "_escaped_fragment_") {
                        set $prerender 1;
                }
                if ($http_user_agent ~ "Prerender") {
                        set $prerender 0;
                }
                if ($uri ~ "\.(js|css|xml|less|png|jpg|jpeg|gif|pdf|doc|txt|ico|rss|zip|mp3|rar|exe|wmv|doc|avi|ppt|mpg|mpeg|tif|wav|mov|psd|ai|xls|mp4|m4a|swf|dat|dmg|iso|flv|m4v|torrent|ttf|woff)") {
                        set $prerender 0;
                }

                #resolve using Google's DNS server to force DNS resolution and prevent caching of IPs
                resolver 8.8.8.8;

                if ($prerender = 1) {
                        #setting prerender as a variable forces DNS resolution since nginx caches IPs and doesnt play well with load balancing
                        set $prerender "service.prerender.io";
                        rewrite .* /$scheme://$host$request_uri? break;
                        proxy_pass http://$prerender;
                }

                if ($prerender = 0) {
                        set $proxy_host $host;
                }

                #proxy_set_header X-Prerender-Token YOUR_OWN_TOKEN;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
                proxy_set_header Host $proxy_host;

                if ($prerender = 0) {
                        proxy_pass http://localhost:3000;
                }
    }
}

After line 55 there is a missing break;. In my case my application didn't work without it.

  if ($prerender = 0) {
                    proxy_pass http://localhost:3000;
                    break;
  }