MyLanguages is a script which bolds and moves to the top of the list some user-defined interwiki links. It aims for simplifying navigation between Wikipedias in languages known by the user.
Setup edit
On your javascript page, corresponding to the skin you use (monobook.js by default, see Wikipedia:Skin for other skins), put the following code:
importScript('User:Lampak/MyLanguages.js');
var mylangsArray = ["fr", "de"];
Replacing "fr", "de" with your chosen language codes, between quotation marks, separated with commas (in the example above the highlighted languages will be French and German). You may include a greater number of languages or just one.