Christopher Su

BBCode Widget Titles is a very simple, lightweight plugin that allows for the use of BBCode in styling widget titles. 
It currently supports the [b], [i], [u], [s], [url=], and [color=]. Simply install the plugin and BBCode will be 
parsed in widget titles.
This plugin has been tested to work up to 3.4.2. Please <a href="http://christophersu.org/contact/" rel="nofollow ugc">contact me</a> if you experience any problems with this plugin or have any questions.

BBCode Widget Titles

Allows for the use of BBCode in styling widget titles. Supports [b], [i], [u], [s], [url=], and [color=].

digitalpoint

The Shortcode Callback plugin allows you to use a [callback] shortcode to execute arbitrary PHP code wherever the shortcode is used.
Usage
Execute someFunction() and insert whatever it returns with the following shortcode: 
 [callback function=”someFunction”]
Example shortcode to include a PHP file (the path is relative to WordPress’ ABSPATH), then insert the results of someFunction() where you used the shortcode: 
 [callback include=”custom/filetoinclude.php” function=”someFunction”]
Shortcode example that includes a PHP file (the path is relative to WordPress’ ABSPATH), then passes a paramter to someFunction() and returns the results where you used the shortcode: 
 [callback function=”someFunction” include=”custom/filetoinclude.php” param=”something”]
The format to call a class/method with the shortcode is exactly the same as above, except you specify the class::method in the “function” attribute of the shortcode. 
 [callback function=”someClass::someFunction” include=”custom/filetoinclude.php” param=”something”]
There is an example (with PHP code) <a href="https://wordpress.org/plugins/shortcode-callback/faq/" rel="ugc">over here</a>.

Shortcode Callback

Adds a [callback] shortcode that can trigger PHP code so you can insert custom/complex things into your pages/posts.

BBCode Widget Titles vs Shortcode Callback