If you want, i can make a special forum section for templates discussion.
As about custom {variables}.. why would you want that ?!
The {variables} are used only for BS special needs, to know where to post the links, the content, etc. Anything else you can add directly in the templates (like banner, Adsense or anything else)
I was thinking along the line that if you put the variable in the template, but left the variable empty, it would be ignored when the page was generated.
But, then you set the variable to something, adsense code, a php snippit, what ever, and have a mass change instantly, and not have to edit any templates.
Just a thought...