This PHP function will take a multi dimensional array and create all its possible combinations (not permutations). I used this function in debug code, but I can see its use in many other cases.
Internationalizing your plugin is not difficult. All the information you need is out there and the WordPress Codex is very good resource, but I thought I’d sum it up for those who need the quick skinny on the matter.
As you begin to build custom UI elements (meta box elements) for your WordPress themes and/or plugins; you may find it useful to hide certain meta data variable names so that they do not appear in the Custom Fields area. There is no point in allowing the user to edit a piece of meta data in both your custom UI and also in the Custom Fields section (IMHO, i think it adds to the clutter and may cause confusion).
Make your WordPress custom meta boxes page specific. The home page is a great example of this: often the main page will contain several unique elements which would benefit from using custom meta boxes, but how do you limit the meta box to the home page only?