1. Add this to the CFBundleDocumentTypes array in /Applications/TextEdit.app/Contents/Info.plist:

   <dict> <key>CFBundleTypeExtensions</key> <array> <string>url</string> </array> </dict>

   1 2 3 4 5 6

   <dict>     <key>CFBundleTypeExtensions</key>     <array>         <string>url</string>     </array> </dict>

2. /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -f /Applications/TextEdit.app/

3. killall Finder
4. 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.

from:http://apple.stackexchange.com/questions/15030/how-can-i-add-a-new-application-to-the-open-with-menu