cavimaster

Simple whois tool in a widget
Post a domain name et submit. 
Whois on widget return to you a complet whois query into Jquery lightbox. 
You can use shortcode like: [WHOIS] for put it in your page or post.
<a href="http://www.devsector.ch/cavimaster/category/developpement/wordpress-plugins-widgets" rel="nofollow ugc">Cavimaster_blog</a>
Original PHP whois code by Sven Cailteux – <a href="http://www.dimension-internet.com" rel="nofollow ugc">Dimension internet</a>

Whois on widget

Mahamodul Hasan Khan

dnsLT is a little tools for Searching Domain whois & showing in any kind 
of WordPress Site. You don’t need to do a simple code for that. Just put 
the ShortCode in your page or post or anywhere it will show a search 
form for domain whois. Then your visitor will able to search any domain 
whois from there. You can config colors with your site color from admin 
settings in free version. also can do many things from pro version.

dnsLT Free domain name whois

A plugin for search domain whois from your lovely web site.

Whois on widget vs dnsLT Free domain name whois