I don't want to make a new thread every time I increase the subversion number, so I'll post my future packARC updates here. For those who do not know, packARC is a "media archiver" uniting my packJPG, packMP3, packPNM and packARI compression algorithms under one hood. Although it will compress any file you throw at it, it will perform best for MP3 and JPEG and it will perform well with PNM and BMP. For other file types it highly depends on their content, in the worst cases packARC may even be outperformed by classic ZIP.
packARC includes it's own source code and is now completely open source under the GPL.
You may download the newest release of packARC v0.7 from my developer blog, more specifically from this subsite. The most recent version as of writing this is: packARC v0.7RC16.
packARC download page on packjpg.encode.ru
As always, I'm thankful for bug reports, if anything should come up.