Sergey Biryukov

Allows to create users with usernames containing Cyrillic characters.

Allow Cyrillic Usernames

Allows users to register with Cyrillic usernames.

Anton Lukin

Simple and fast plugin for Russian-language blog. Converts cyrillic characters in posts, pages, terms and file names. 
Declension of nouns in Russian dates. Recommended to use for all fresh-installed Russian-speaking audience sites.
You can contribute this plugin on <a href="https://github.com/antonlukin/rus-package" rel="nofollow ugc">Github</a>.

Rus Package

Snippets for Russian-language blog. Cyrillic to Latin converation in slugs and declension of nouns in dates.

Allow Cyrillic Usernames vs Rus Package