darrinb

Easily include raw markup languages (HTML, CSS, PHP, etc.) in comments using custom quicktags. No need to encode, the filter does it for you. Creates convenient “encode” buttons for comment authors in the HTML editor.
Also adds basic quicktag buttons on the comment forms, using the Quicktag API built into WordPress (as of 3.3).

WP Comment Encode

crille

Non-ASCII characters can be used in the URL, but they have to be encoded (RFC3986). URL encoding is widely used (e.g. Wikipedia http://ja.wikipedia.org/wiki/Wikipedia:%E9%80%A3%E7%B5%A1%E5%85%88). 
This plugin encodes NON-ASCII characters in the slugs of your pretty permalinks. So your slugs may look like <code>fußball-in-nürnberg</code> or <code>連絡先</code>.

Permalink Encoding

This plugin encodes NON-ASCII characters in pretty permalinks by using Percent-Encoding described in RFC3986.

WP Comment Encode vs Permalink Encoding