Global Page?

I'm using New Blog Templates to create blogs by template.
Have a growing network of blogs, with standard pages, like HowTo, stuff that gets updated frequently and needs to be current for all my users across all blogs.

The template, stamps a copy of the page, "as of a time", often long ago. So these pages, become stale... When they need to be current.

Is there a plugin/utility like "Global Content Blocks", except that pulls content from a php file on the server, instead of the database that's part of the blog?

This way I can put the "common stuff" in a file on the server, and then pull it into a blog at load time. This way, I only have one copy of the "file" to maintain.