Any good translation platform as engine (or as saas)?

Hi, I need to translate in a crowdsourcing way my website. While ago I tried Tolk ( which is nice, but I'm looking for something else.

Is there anything like the Twitter platform ( )?

Something with ranks, eventually gamifications and stuff like that. In order to give [real] prizes to the best translators. Something directly integrated (as an engine) would be better, otherwise a saas which permit single sign on access in order to use (and track) the existing user accounts