How can I add a new application to the Open With menu?
Add this to the CFBundleDocumentTypes array in /Applications/TextEdit.app/Contents/Info.plist:

&lt;dict&gt;
    &lt;key&gt;CFBundleTypeExtensions&lt;/key&gt;
    &lt;array&gt;
        &lt;string&gt;url&lt;/string&gt;
    &lt;/array&gt;
&lt;/dict&gt;

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -f /Applications/TextEdit.app/
killall Finder
Change the default application back to Safari in Finder


If the application is signed, modifying an Info.plist invalidates the code signature. It also makes a few applications like TextEdit and WriteRoom crash on launch on 10.8.