Public IP's on TMG

I have a TMG Firewall as my firewall. I need to publish some ports on the web, for example port 80. The problem is that I need to publish more than one thing on the same port. I have more than 1 public IP which I currently do not use (I only use 1).

What is the best thing that I do so I can publish more than 1 service on the same port?

Thanks,
J