marco_b

This is a plugin / widget, after installing you have the possibility to locate a widget to your site. An visitor can now send a sms to a person.

SMSPlug

With this plugin you can use the service from aspsms.com. It allows you to send sms via their service.

luzifer

With this plugin you get a new widget on your dashboard showing you every post on which 
you haven’t commented as last person. This is very usefull for blogger who wants to give 
the attention to their commenting readers they should have.
So if you try to reply on every comment because its good behaviour in your sight this plugin 
will help you not to miss one of them.

WP-Show-Unresponded-Comments

This plugin adds a widget to your dashboard showing every post which has a comment…

SMSPlug vs WP-Show-Unresponded-Comments