Sencha CMD is a must-have if you're doing any professional ExtJS or Sencha Touch app development. You can always get the latest version from Sencha's product page, but what if you wanted to get an older version? Sure, upgrading to the latest version is an option, but we all know how smooth those upgrades can go (or not, especially if you messed with the build scripts).
Older versions with release notes are available via this URL pattern:
So, the caveat is that you have to know the exact version which you're after!