mohanjith

Code Master

Helps you make the site available via https and http with no effort. Just install and activate 
and say good bye to SSL errors without forcing users to access via http or https only.
<h3>Notes & Credits</h3>
This plugin is written by <a href="http://mohanjith.com/" rel="nofollow ugc">S H Mohanjith</a>.
You should follow us on Twitter <a href="http://twitter.com/codemasteroy" rel="nofollow ugc">here</a>.

WordPress SSL

Have been using this plugin to resolve SSL errors for quite a while.  Has not failed and works just as advertised.  Ensures all links to resources are on the correct protocol.

Has worked well for a long period

Seamlessly map URLs to SSL if the site is accessed via SSL.

blackc2004

This plugin will make sure that all elements on a page are SSL if the page is being accessed via HTTPS. For this to happen you must have used correct programming practices and use siteurl, wpurl, url etc where all the locations are supposed to be.
Some plugins do not correctly use this, I have already notified a few of them, but you may find some other issues, if you do, please contact me and I will research and attempt to notify the developers of the other plugins.

HTTPS for WordPress

Check to see if SSL is used. This will update any template functions which require SSL to be used.

WordPress SSL vs HTTPS for WordPress