Mango
This is general name for number of projects, which aim is to provide search source over social data (Twitter, Facebook) and make easier reuse of social data for other teams and services in Yandex. Page is password protected, so please request password from me.
Offline search
Offline search in MapReduce paradigm.
Document annotations
Is a short text (approx. 170 symbols long), which appears at search engine results page after query processing.