My ISP, RCN, blocks incoming requests to port 80. I've used No-ip to redirect requests to my domain to my (dynamic) IP address on port 8080. These are then forwarded through my router (running openwrt) to my web server (a $45 Raspberry Pi. 2 watts!)

However, this config results in users seeing the following in their browser's address bar:
mysite.net:8080

Is there a way to set things up such that nginx can reverse proxy requests on port 8080 to itself on port 80, and hide the port number in the visitor's address bar? Or is there a better way to do this? (aside from paying my ISP $20 more a month for a static IP and an unblocked port 80)

I took a look at this and found some hope, but I'm not sure if it will work in this situation:
http://www.ubuntugeek.com/using-nginx-as-a-reverse-proxy-to-get-the-most-out-of-your-vps.html