karevn

This plugin adds simple HTML tag generation API to WordPress, like these examples: 
 generates and prints <code><img src="/wp-content/<your-theme>/images/wordpress.png" alt="Wordpress" /></code>. 
 ‘my-image’)) ?> generates and returns almost the same tag, just with absolute url, id and alt attributes set manually. 
 term_id) ?> generates select tag with options taken from WP ‘category’ taxonomy and sets $term as selected item 
 rails-like “cycle” that returns “odd” on first call, “even” on second, “odd” on 
 third call, so on. reset_cycle resets the cycle. 
 shortcut for echo(get_post_meta($id, ‘meta_name’, true))
Form field generators for <code>text</code>, <code>checkbox</code>, <code>hidden</code> input types, <code>textarea</code>, and more tags. More docs coming soon, you can read the code to figure out other features for now.

HTML Helpers

This plugin adds simple HTML tag generation API to WordPress.

Sharaz Shahid

Code Widget is simple widget allows you to insert any arbitrary Text/HTML and run PHP Code or Short Code. This Widget parses PHP code into simple text and much more.
Only users with the unfiltered_html role will be allowed to insert unfiltered HTML. This includes PHP code, so users without admin or editor permissions will not be able to use this to execute code, even if they have widget editing permissions. 
This plugin is developed and maintained by <a href="https://twitter.com/sharazghouri1" rel="nofollow ugc">Sharaz Shahid</a>

Code Widget

Code widget help  to  add  Short Code, PHP Code, HTML, and Simple Text in widget.

HTML Helpers vs Code Widget