G-Cows is a scripting language, so it's up to you to find out what it can be useful for. The following are just some ideas:
You can define mail addresses, release versions, file names used in links etc. as variables. By doing so, you can change a definition once and see changes spreading all over the site. You can also include external files in multiple places; again you can change one thing and update every page depending upon it.
You can simplify your HTML code by defining common sequences of HTML tags as variables.
You can give a consistent look to your site including a common header and footer in every page.
G-Cows allows, when used in conjunction with Make, to change a file and update all and only pages depending upon it.
Contents usually change faster than layouts so it's a good practice to keep them separated. Also, it will make much easier to keep multiple versions of a web site, differing in contents (e.g. different languages) or layout (e.g. a more complex version and a simpler one for older browsers or visually impaired users).
You can include the same file in multiple places and change its behavior according to the situation.
G-Cows is designed to integrate itself with your Unix (or Linux) system in two ways:
Cows-mkgen generates makefiles allowing to handle complex dependencies among site elements;
the Cows interpreter is able to execute commands, scripts and programs written in every language whose interpreter or compiler is installed on your machine.
When using both features, your system provide both a high level director (Make) and an endless source of features ready to be called by cows scripts (every command and every program with a command line interface).
This manual can be downloaded from http://www.g-cows.org/.