host config

# /etc/nginx/sites-enabled/berlin
upstream spree.ryanbigg.com {
  # fail_timeout=0 means we always retry an upstream even if it failed
  # to return a good HTTP response (in case the Unicorn master nukes a
  # single worker for timing out).

  # for UNIX domain socket setups:
  server unix:/tmp/berlin.socket fail_timeout=0;
}

server {
    # if you're running multiple servers, instead of "default" you should
    # put your main domain name here
    listen 80 default;
    listen 443 ssl;

    #ssl on;
    ssl_certificate /etc/ssl/certs/spree.ryanbigg.com.crt;
    ssl_certificate_key /etc/ssl/private/spree.ryanbigg.com.key;

    # you could put a list of other domain names this application answers
    server_name spree.ryanbigg.com; 

    root /home/spree/berlin/current/public;
    access_log /var/log/nginx/berlin_access.log;
    rewrite_log on;

    location / {
        #all requests are sent to the UNIX socket
        proxy_pass http://spree.ryanbigg.com;
        proxy_redirect     off;

        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto  $scheme;


        client_max_body_size       10m;
        client_body_buffer_size    128k;

        proxy_connect_timeout      90;
        proxy_send_timeout         90;
        proxy_read_timeout         90;

        proxy_buffer_size          4k;
        proxy_buffers              4 32k;
        proxy_busy_buffers_size    64k;
        proxy_temp_file_write_size 64k;
    }

    # if the request is for a static resource, nginx should serve it directly
    # and add a far future expires header to it, making the browser
    # cache the resource and navigate faster over the website
    # this probably needs some work with Rails 3.1's asset pipeline
    location ~ ^/(spree|assets)/  {
      root /home/spree/berlin/current/public;
      expires max;
      break;
    }
}

nginx config

user spree;

# Change this depending on your hardware
worker_processes 4;
pid /var/run/nginx.pid;

events {
    worker_connections 1024;
    multi_accept on;
}

http {
    types_hash_bucket_size 512;
    types_hash_max_size 2048;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay off;
    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    gzip on;
    gzip_disable "msie6";

    # gzip_vary on;
    gzip_proxied any;
    gzip_min_length 500;
    # gzip_comp_level 6;
    # gzip_buffers 16 8k;
    # gzip_http_version 1.1;
    gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}

Wanted to mention that this helped along with this key piece of information

I added this in the spree.rb in config initializers

SslRequirement.module_eval do
  protected
    def ssl_allowed?
      true
    end
end

wickchucked, this did it for me as well. Thanks for posting that!!