I thought I should mention that toollabs:not-in-the-other-language can be very useful for users when choosing an article to translate. Just set a language pair such as "es" + "pt" and a category from the first language Wikipedia, and you'll have a list of articles of your interest to choose from. Examples:
Topic on Talk:Content translation
That is useful. We are working on integrating similar functionality into Content Translation in order to suggest articles that can be translated.