Matheus Eduardo

This plugin adds a new field (metadata) in the section editing links in order to add social networking links (like <a href="http://twitter.com/" rel="nofollow ugc">twitter</a>, <a href="http://flickr.com/" rel="nofollow ugc">flickr</a>, etc.) to any link.
PT-BR 
Este plugin acrescenta um novo campo (metadados) na seção de edição de links para poder adicionars links de redes sociais (como <a href="http://twitter.com/" rel="nofollow ugc">twitter</a>, <a href="http://flickr.com/" rel="nofollow ugc">flickr</a>, etc) a um link qualquer.

Simply Social Links

This plugin adds a new field (metadata) in the section editing links in order to add social networking links (like twitter, flickr, etc.) to any link.

Daniel Westermann-Clark

By default, WordPress network usernames cannot contain anything but lowercase letters and numbers. This plugin adds network options to let you include hyphens, underscores, or uppercase letters, if desired.
Furthermore, this plugin gives you the option to allow email addresses as usernames, or to allow all-numeric usernames (e.g. “1234”).
Finally, this plugin lets you override the minimum length for usernames (which defaults to four characters).
To follow updates to this plugin, visit:
https://danieltwc.com/
For help with this version, visit:
https://danieltwc.com/2011/network-username-restrictions-override-1-0/

Network Username Restrictions Override

Does what it says!

Override restrictions on WordPress network usernames.

Simply Social Links vs Network Username Restrictions Override