If you ever had trouble with WordPress generating non-valid RSS or Atom feeds, this is the plugin for you.

This plugin will convert ISO-8859-1 data to UTF-8 data in a MySQL UTF-8 WordPress database where things at some stage went wrong.

Allows you to enter national characters in username during registration.

Easily Converts the WordPress database from any type of character set to UTF-8 character set.

This plugin is designed to handle the broken characters that might appear on your blog posts, if their content is converted from/to UTF8 and ISO-8859-1.