Ok, so I have a website and want to accept Bitcoin tips or offer PPV content etc. I put up a file link - http://mysite.com/tipme.bitcoin
Future bitcoin Win installers would (optionally, by default) make appropriate Windows file extension associations to forward *.bitcoin file metadata to bitcoin.exe, which in turn automatically populates "pay to" and "amount" fields. The end-user would simply have to click "Send". Perhaps there could be safeguards (configurable) in place to limit "amount" values.