ERIC DEL SESTO  This works well, in fact for some reason it works better than the manual approach (which is to enter 'defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1' in Terminal). On a brand new iMac with OSX 10.5.5 I tried the manual approach, and it did not work. I used 'defaults read com.apple.systempreferences' to confirm that the 'defaults write' command had worked, but Time Machine was still not showing my external (AFS mounted) volume, even after a reboot. I upgraded to OSX 10.5.6 and still the manual approach was not working. I then downloaded and ran this utility and now Time Machine shows that external volume. I can't explain why this utility works better than the manual approach; perhaps it is doing something to cause OSX to re-read preference flags. Thanks, Antonello for creating this. Saved my evening! - Eric  
(Version 1.0b)