Developer Michael Lee discontinued (most of) his Photo Tools page. This includes the official downloads of packJPG Options and packMP3 Options, which are excellent graphical user interfaces for packJPG and packMP3.
You may find the downloads for most recent versions of both tools in the packJPG and packMP3 sections of this page now. While you’re at it, you might also give Michael’s excellent GPStamper tool a try.
On another, slightly related note, expect the LGPL release of packMP3 and packARC soon!