I see that in the admin settings you can change the Product Detail Page Layout for products
How do you add a new entry to the drop down? Right now I only see two default templates but I want to create a third and forth one for my custom purposes but I don't see how to add them to the list.
Just put your file in skins/your-skin/customer/blocks/product_templates
The drop down will pick it up after you clear your cache.
The file will come up with a weird name, but it will be there. I think you could add it to your languages though to get a better name.
For example, if I put a file there called
brandon_template.tpl
It will show up as _brandon_template
I'm pretty sure that if you were to put _brandon_template as the variable and Brandon Template as the value in your languages, it will come up just fine.
Hope that helps,
Brandon