I don't think there is much at the moment.
When you create a language override select the language file you want.
The variable name you want to override, for example:
and then the name of array element, for example:
And finally the Value you want to replace the text with
Using this example the Welcome message at the top of the Geeklog site will be changed to what ever you specified.
One of the Geeklog Core Developers.