Bukkit

As of version 0.5 the whole interface can be customised. Meaning you can change the items, values for the currencies and even move around all of these.

There is one limitation, you can only make custom layouts for interfaces of 6 rows ( double chest size ) this will be changed if future versions

In the default layouts.yml, which can be found here, two templates are given. The 'template-default' is the default layout for an interface of 6 rows. The 'template-currency' is the default layout when the economy mode is enabled.

All values in the layouts.yml are optional if one of them is not specified it will take the default values.

To use a certain layout one has to be sure that a the option 'default-rows' is set to 6 and that the name of the custom layout is specified under the 'custom-layout' in the config.yml .

Final note: The plugin will not check correctness of the layouts. So be sure to check your layout before using it.