Henry Wright

This BuddyPress plugin sends notifications to a collection of members when you use a command to mention them. Supported commands are:
<ul>
<li>@friends</li>
<li>@group</li>
<li>@moderators</li>
<li>@administrators</li>
</ul>

Crowdmentions

This plugin makes it easy to broadcast an @ mention to an exact subset of members.



very useful

Use a command to mention a collection of members on your BuddyPress site.

Raulanton

This ultra light-weight plugin send a customizable notification email to each user/author mentioned in a comment.
Mentions: A mention is an username preceded by the mention qualifier.
Username: This plugin will look for the username in display_names and logins. Multiple authors could be mentioned in a comment.
Qualifier: Can be a character but also a string. 
The default qualifier is ‘@’ to work as in Twitter, but it could be changed via admin menu to be ‘#’ or even an string like ‘Mention:’ .
Email:
The email can be customized to include or not the whole comment in wich the mention is. 
The email can be customized to add a reference to the mentioner profile at the site. 
It is also possible to define email header and footer. 
The email can include the URl to the comment in which he/she was mentioned
I18N:
This plugin is I18N (es_ES, en_US, fr_FR) 
Any help with translations will be nice!

Email Mentioned

Email Mentioned is a lightweight customizable -no coding needed- plugin to send an email to each user mentioned in comments.

Crowdmentions vs Email Mentioned