ab-tools

A simple plug-in that displays flag icons.
This plug-in does not provide a way to translate posts directly, but offen you do not want a direct translation of posts. Still you want to add flag icons that link to other language versions of your blog.
After installation of this plug-in a new widget will be added that you can use to display such flag icons on your blog. A set of flag icons is included, but if you want to use your own images that’s possible, too.
<h4>Additional info, support and developer contact:</h4>
<ul>
<li>English: http://www.ab-weblog.com/en/wordpress-plug-ins/flags-widget/</li>
<li>German: http://www.ab-weblog.com/de/wordpress-plug-ins/flaggen-widget/</li>
</ul>
Please let me know if you find a problem with this plug-in or have questions!
<h4>You can see this plug-in in action on posts of this blog:</h4>
<ul>
<li><a href="http://www.ab-newsonline.com/en/" title="Read Current News Online at AB-NewsOnline.com" rel="nofollow ugc">Read Current News Online at AB-NewsOnline.com</a></li>
</ul>
If you like this plug-in, please <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=donation%40breitschopp.de&item_name=Donation%20for%20Flags%20Widget%20WordPress%20Plug-In&no_shipping=0&no_note=1&tax=0&currency_code=EUR&lc=CA&bn=PP%2dDonationsBF&charset=UTF%2d8" title="Donate With PayPal" rel="nofollow ugc">consider a donation</a> to keep it free. Thank you! 
… and please don’t forget the 5 star rating, if you like this plug-in. 🙂

Flags Widget

A simple plug-in that displays flag icons that link to other language versions of your blog.

azurecurve

Allows a 16×16 flag to be displayed in a post of page using a [flag] shortcode.
Format of shortcode is [flag=gb] to display the flag of the United Kingdom of Great Britain and Northern Ireland; 247 flags are included.
Defintion of flags can be found at Wikipedia page ISO 3166-1 alpha-2: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

azurecurve Flags

Allows a 16x16 flag to be displayed in a post or page using a shortcode.

Flags Widget vs azurecurve Flags