Do dualingo has also an option to reverse translation: from English to German or from English to Spanish?
IMHO this could be much more useful for learning a language
No, it is oposite. Currently the only option is Spanish/German to English. This way i feel more learning English, rather than Spanish or German. To learn Spanish or German it would be much more usefull, if I had to write in Spanish/German. Also, I think it could be usefull for wikipedia to translate content from English, to other languages (as the most part of info in Wikipedia is in English).
@ K_Lamberts Don't forget that the main purpose of Duolingo is to translate the web - teaching us the language is just the incentive to get us to do that. In translating, it is always much better (and easier) to translate from your secondary language to your primary language. You have a better feel for your primary language and are therefore able to make better sentences. Having said that, it looks like they do have it set up now to learn English if your primary language is Spanish, so you could try that out. From the main page there's a drop down menu at the bottom left to choose Spanish as your primary language.