Oren Yomtov

1.7: 
WordPress 2.9.1 compatible.

This plugins allows you to add your own buttons to the post edtor’s toolbar. 
I’m talking about the buttons that you see above your content text area when editing posts (b,i,link,img,ul,li). 
For example you can add a “h3” button to make subheaders in your post. 
There are virtually endless buttons you can add.

<a href="http://orenyomtov.com" rel="nofollow ugc">Yomtov</a>
<a href="http://twitter.com/orenyomtov" rel="nofollow ugc">You should follow me on twitter</a>

Post Editor Buttons

This plugin allows you add your own buttons to the post editor's toolbar.

Kailey (trepmal)

Add custom buttons to the TEXT mode editor toolbar.
This is a fork of <a href="https://wordpress.org/extend/plugins/post-editor-buttons/" rel="ugc">Oren Yomtov’s</a> plugin.
Unsure of the reason behind the poor rating and “doesn’t work” vote. Possibly the user didn’t realized this only adds tags to the HTML editor? If you use this plugin and it works for you, I’d appreciate it if you’d give my a good star rating and an “it works” vote.
Conversely, if you have trouble, please post to the forums, and/or ask me on <a href="http://twitter.com/trepmal" rel="nofollow ugc">twitter (@trepmal)</a>.
If you need this to work on WordPress < 3.3 download <a href="https://wordpress.org/extend/plugins/post-editor-buttons-fork/download/" rel="ugc">2.2.1</a>.
<ul>
<li><a href="http://twitter.com/trepmal" rel="nofollow ugc">I’m on twitter</a></li>
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Post Editor Buttons Fork

Doeas what it says. It is super useful for creating i.e. hX tags or shortcodes i.e. [button].
I don't like the visual editor, so this additions are great.
PS. The code could be more tidy.



Super easy and super useful

When you have to edit content in HTML and insert a lot of the same classes, this plugin becomes precious, as it let's you customise your HTML editor buttons in a rather simple way.

There are 2 things I miss, and that's why I'm giving it 4 stars: 
– a way to re-order the created buttons
– a way to export and import the created buttons

BTW, it seems to be working fine with 4.8.

Very handy

This plugin allows you add your own buttons to the post editor's TEXT mode toolbar.

Post Editor Buttons vs Post Editor Buttons Fork