Ono Oogami

This little plugin allow customing the “date base” of date (month, year, day, etc.) archive page. For example, by default your blog’s monthly archive page’s permalink is like: “http://example.com/date/2010/05/”, with this plugin you can change the string “date” to others, just like the feature of changing permalink’s category base and tag base which is built in WordPress.
Note if your blog’s permalink structure is “/YYYY/mm/dd/post-slug/”, this plugin will not take effect and your blog’s permalink of date archive page would be “/YYYY/mm/”.

Date Permalink Base

Allow customing date base of archive page permalink .

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.

Date Permalink Base vs Permalink Encoding