This plugin can detect information such as country name, web browser and operating system from your commenters and then displays them on your comment section or anywhere you like.
Features:
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Detects and shows commenter?s country flag, web browser and operating system automatically
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Supports many web browsers and operating systems: major desktop browsers, antiquated browsers, blogging software (for trackbacks and pingbacks), text based browsers, various PDAs and cell phones.
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Uses a binay file for IP to country resolution and supports database sources from Webhosting.info – Software77.net
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The returned string can be configed as a template to suite your theme
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<h3>Credits</h3>
Especially thanks to
<ul>
<li>
<a href="http://priyadi.net/" title="Priyadi Iman Nurcahyo" rel="nofollow ugc">Priyadi Iman Nurcahyo</a> for his <a href="http://priyadi.net/archives/2005/03/29/wordpress-browser-detection-plugin/" title="WordPress Browser Detection Plugin" rel="nofollow ugc">WordPress Browser Detection Plugin</a>
</li>
<li>
<a href="http://firestats.cc/" title="Omry Yadan" rel="nofollow ugc">Omry Yadan</a> for his <a href="http://firestats.cc/wiki/EasyIP2Country" title="Easy IP2Country" rel="nofollow ugc">Easy IP2Country </a> plugin
</li>
</ul>

Comment Info Detector

Enables you to detect your commenter's info and show their country flag, web browser, operating system automatically.

ppatux

Simple IPv6 detector widget for WordPress to show if user is connecting with IPv6 or IPv4.
Additionaly, it makes a link to a whois service with the ip address.
It was born because of my own blog. I needed to include a little box that shows users ip and different messages depending on the ip version.
The idea behind this is to promote and leave a way to discover and make sense about the ipv4 address space limits.

IPv6 Detector

Simple IPv6 detector widget for WordPress to show if user is connecting with IPv6 or IPv4.

Comment Info Detector vs IPv6 Detector