dotSUB!

Amara (formerly Universal Subtitles or unisubs) gives individuals, communities, and larger organizations the power to overcome accessibility and language barriers for online video. The tools are free and open source and make the work of subtitling and translating video simpler, more appealing, and, most of all, more collaborative.The benefits of captioning and subtitling are immense:Captions make videos accessible for viewers who are deaf or hard of hearingTranslations make it possible for all of us to watch video in languages that we don't speakVideo creators get: better SEO, more views, access to a far bigger (potentially multilingual and global) audience, accessibility for deaf and hard of hearing viewers, and more »

In contrast to http://translated.by/ it is more convenient for translations by smaller chunks. In contrast to http://www.addic7ed.com/ it has an integrated message board system and provides an opportunity of book and phrase collective translation as well. Phrase\sentence translation projects are being created for all available languages simultaneously.The website is mainly aimed for Russian audience, though others are welcomed as well.

Overstream allows you to "overstream" videos from popular videosites and add supplementary subtitles, commentary, and captions to them.

It's called collaborative translation. To make it simple, people help each other translate interesting foreign language texts into their native language. It's mostly blog posts, magazine articles, short stories and another materials licensed for free redistribution.