wladweb

Plugun show twitter user timeline, home timeline, mentions, home timeline another user, search result by post tags, category name and any words. 
Tweets can be show in widget and also in home page between posts in main loop.

Tweettee

Plugin can show tweets in widget and in home page.

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.

Tweettee vs Email Mentioned