Mark Jaquith

Redirect Old Slugs allows you to change your post slugs without breaking your permalinks. People requesting the old link will be redirected to the new link. This all happens automatically.
Note that this functionality was brought into WordPress core for version 2.1, so this plugin is not needed. When you upgrade to WordPress version 2.1 or higher, your old slugs will be kept and will keep on being redirected without the need for this plugin.

Redirect Old Slugs

Allows you to change your post slugs without breaking your permalinks.

Sergey Biryukov

This plugin is available for reference only. Its functionality has been replaced and extended by <a href="https://wordpress.org/extend/plugins/cyr2lat/" rel="ugc">Cyr-To-Lat</a>.
The original author of this plugin is Anton Skorobogatov, who passed away prematurely in 2007. I decided to make it available for installation through the Plugin Browser/Installer. I take no credit for the creation of this plugin.
Converts Cyrillic characters in post slugs to Latin characters. Very useful for Russian-speaking users of WordPress. 
You can use this plugin for creating human-readable links.
Thanks to Alexander Shilyaev for the idea.

Rus-To-Lat

Converts Cyrillic characters in post slugs to Latin characters.

Redirect Old Slugs vs Rus-To-Lat