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.

Nimbus Digital

Redirects http://somedomain.tld to http://someotherdomain.tld
Assuming you have 2 or more domains in use for a single WordPress site. This plugin forces the use of only one no matter which is entered in the address bar.
If, for some reason, your host won’t automatically redirect from one domain to another, then this plugin will do it. It checks the URL used to access the site and does a 301 redirect if incorrect.
In theory htaccess should do this, but in my case it didn’t. Perhaps because I am using domain aliases (or CNAMEs) and I wanted to insure that the main one was always in use, even when accessed using old links.

Force Domain Redirect

Forces your Wordpress site to load on the domain registered in the WP admin.

Permalink Encoding vs Force Domain Redirect