I upload a new page today with code to create Zip files with the free Zip program 7-zip.
This program is also very useful if you want to open Office 2007 files as a archive
without changing the extension to .zip so you can see/edit the files in the archive.
Zip Activeworkbook, Folder, File or Files with 7-Zip (VBA)
I will add a Unzip page to my site for 7-zip it next week
For examples for WinZip or the default Windows Zip program see the Zip (compress) section here
Have fun and let me know if you have suggestions or find a bug