Adding default widgets not specific to theme

Is there a way to add to the default widgets without specifying them in a theme or modifying the default_widgets.php file? I would like to add some non-theme specific widgets but I do not want to have to worry about overwriting the default_widgets file every time I upgrade. I was hoping there was some kind of hook that automatically includes another file like more_default_widgets.php from the wp_content root folder.

Thanks,

Pete