Customer Portal Customization - Adding custom placeholders
I am trying to modify the customer portal within Setup -> Portal Customization. I wish to add a couple of new placeholders in the tabbed menu. I can see from the HTML Editor that I can add pre-defined placeholders but how can I add custom placeholders where the content of the placeholders will be a webpage from a specific url? For example, I would like an extra placeholder called "Downloads" which reference a website at
http://www.mydownloads.com and display this website within the content. Furthermore, I also need to access the email of the customer who is signed in to the customer portal in order to pass that email address to the website.