That is a good idea. In terms of the legailty of it, aslong as you have the authers permissions to put it up on the site then I can't see why it would be any more illegal then the auther putting it up on Aminet.
The program would be best to sit in the background as a comodity or something, and only pop up when it is aware of you library etc being out of date. It then gives you the option to ignore it and carry on without the update, or download and install it. It should also make backups of the old libaraies incase the new one is a bit buggy or what ever.
Just my 2c worth!
JS
