So despite what
http://code.google.com/chrome/apps/docs/developers_guide.html
says about the .crx file just being a .ZIP file, it's actually not.
If you create it with standard zip tools and re-name it .crx, when you
open a link to the CRX file in Chrome, it will try and download it
instead of installing it.
You need to pack the app using the following command line:
<path-to-dev-channel-chrome>\chrome.exe --enable-apps --pack-
extension=<path\to\app\folder>
This will create a valid .crx file
Now if you open Google Chrome with --enable-apps and click on the
following link:
http://worldofsolitaire.com/WorldOfSolitaire.crx
It will automatically ask you if you want to install the application.
Nice!
Funny enough you can still extract it with normal .zip tools, so it's
still a valid zip, it just must have some special magic in it that is
only put there when created with Chrome itself.