http://wonderwinds.com/hackblog.php/2008/04/13/aggregate-all-blogs-in-v241 shares a hack I just did because I finally needed it.

What it does is let you use the word "All" instead of a comma separated list of blog numbers. In this case "All" actually means "all publicly visible blogs" so if you use #12 as your linkblog and do not display it in your public blog list then it won't aggregate into whatever you aggregate 'All' into.

The download link will give you a zip file that will unzip to become an "inc" folder. In that folder is 14 files: 7 originals and 7 modified versions, with _ORIGINAL added to the file name for the originals. This way if you find a fatal flaw you can go back to the original files with only a minor amount of work.

Okay there ya go!