How can I convince Safari to be responsible for ttp:// URLs as well as http:// URLs?
You can tell Safari to open ttp URLs by adding this to ~/Library/Preferences/com.apple.LaunchServices.plist and restarting (logging out and back in isn't enough).

&lt;dict&gt;
    &lt;key&gt;LSHandlerRoleAll&lt;/key&gt;
    &lt;string&gt;com.apple.Safari&lt;/string&gt;
    &lt;key&gt;LSHandlerURLScheme&lt;/key&gt;
    &lt;string&gt;ttp&lt;/string&gt;
&lt;/dict&gt;


I don't know how to redirect them to http URLs though.