HAProxy is a great load-balancer and proxying software. Typically, HAProxy is installed on a dedicated box but in my colo environment, I have started using it on my firewall. After all, the traffic has to pass through my firewall anyway, so I might as well eliminate yet another box. In my colo, I'm given a /29. That's only 5 usable IP addresses. My virtualization host needs a public IP for management, pfSense needs a public IP, and then my current reverse proxy has a public IP (a virtual IP on pfSense), and now I have only two IPs left. Oh, I almost forgot. I have a VPN server that chews up another.