- Use content types:
Declare a content type for those document libraries, and the use a content query web part to search the entire site collection for all documents of that content type.
- Use custom meta data:
Define a custom field (like I see you are doing) in all the libraries, and use a content query web part to search the entire site collection for all documents which that custom field equals to "true" (for example)
The solutions above both use the Content Query Web Part which is only availalbe if you have MOSS and not just WSS (which you indicate that you do have).
If you dont, you can purchase a 3rd party web part (search google for "aggregation web part") that does similar functionality.