yoav.aner

<a href="http://blog.gingerlime.com/ajaxizing/" title="WordPress plugin that allows you to ajaxize almost any php function on your site" rel="nofollow ugc">Ajaxize</a> will allow you to ajaxize almost any php function on your site. 
It can be a plugin, a function you wrote, or even a core wordpress function.
1.4 : Removed deprecated split function 
 Added an option to remove Ajax referer protection (not recommended, but helpful in some rare cases) 
 Tested for compatibility with WordPress 4.x
1.3 : Updated to work within 404 templates (thanks to ovidiubica for reporting)
1.2 : Small security improvements (added nonce to the javascript) and tested with WordPress 3.2.1
New in 1.1: Context Awareness. Ajaxize is now setting the correct context for functions automatically. Special thanks to <a href="http://digitalnature.eu/" rel="nofollow ugc">One Trick Pony</a> for helping set the hook in the right place.

Ajaxize

Ajaxize will allow you to ajaxize almost any php function on your site.

Tessa (they/them), AuRise Creative

sevenspark

Contact Form 7 – Dynamic Text Extension

With this great plugin, we were able to easily fulfil a customer's request for an extension. 
Thanks a lot

Great Plugin

Extends Contact Form 7 by adding dynamic form fields that accepts shortcodes to prepopulate form fields with default values and dynamic placeholders.

Ajaxize vs Contact Form 7 – Dynamic Text Extension