Amara!

dotSUB is a browser based self contained system for creating and viewing subtitles for videos in multiple languages across all platforms, including web based, mobile devices, and transcription and video editing systems. It's easy and free to use, no application needs to be downloaded for it's usage. One can upload his own videos, transcribe and time caption them, translate them into and from any language, and share them with the world. Another important feature, that dotSUB provides, is the option to embed the dotSUB player onto most websites and blogs with full dotSUB functionality. »

Localize is a very convenient service that provides SDK and online update for iOS and Android apps translation. You can manage your localisation files without the need to think about which version of the app you're updating. You also don't need to recompile the app each time you add a new language.

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.