How do I access port 80 from browser?

I just recently setup my app on my droplet and I can’t seem to access the webserver at port 80 via the ip address:

Here’s my iptables -L:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination  

And my nmap -p 80 localhost:

Starting Nmap 6.40 ( http://nmap.org ) at 2014-12-18 22:26 EST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00017s latency).
PORT   STATE SERVICE
80/tcp open  http

Nmap done: 1 IP address (1 host up) scanned in 1.09 seconds

I can curl localhost from within the server but I can’t seem to access the app using the IP address on a browser. It says that the web page is not available.

Am I missing something that I need to do? I don’t want to use nginx or apache yet. I just want to run a daemon of my ruby server like this: rackup -p 80 -D.