Antonella Perazzoni wrote:
I want to gain more experience in translation by participating as a volunteer in a translation project to add to my resume. Do you know any sites where I can apply? Besides Translators Without Borders, TED and Wikipedia
TWB and, I think, the ones mentioned by Teresa, need their translators to work totally autonomously, with proofreaders rarely being used and feedback rarer still. All you'll get is "thanks" from someone who may have no idea of the quality of your work. It follows that they are looking for very experienced translators who are willing to pay something back by donating their time. Such NGO translations really aren't suitable for beginners.
The crowd-sourced sites such as TED and Wikipedia are different. They are ideal for beginners. Your peers will provide their feedback through their edits.