A friend and I put together this module to be able to manage a lot of FreePBX extensions all at once. When we have to change two or three hundred extensions, using the Extensions page to do them one at a time got a little frustrating.
Anyway, to try it out, see ticket 2826 for usage details. Download the .tgz file from ticket 2826 and use the FreePBX Module Admin page to Upload Module to your server.
Thanks, Seth