robmiller

wp-expurgate looks for HTTP links on your HTTPS site and converts them to HTTPS by running them through a proxy — so every connection between your site and your users is still encrypted.

wp-expurgate

Run your blog on SSL? Tired of seeing mixed content warnings if someone posts a non-HTTPS image on your blog? Problem solved!

Pierre-André Boissinot

Semio Design

This plugin detects if a visitor is using some old version of Internet Explorer and suggests to upgrade to a recent browser. 
The versions to block can be configured in an admin panel. 
Works for blocking IE6, IE7 and IE8. 
Localisation of the plugin into french.

Stop Oldies

This plugin detects if a visitor is using some old version of Internet Explorer and suggests to upgrade to a recent browser.

wp-expurgate vs Stop Oldies