WordPress plugins are insanely popular. Create a good, unique WordPress plugin and you will have plenty of buyers ready to snap it up for a hefty sum.
Becoming a WordPress plugin developer is not as difficult as it may seem. Granted you will have to pick up the basics of using PHP, but that is not as intimidating as it may seem. Learning how to create usable PHP is no different than any other Computer based code. You use many of the same code in every plugin. As a matter of fact, there are a couple of plugins in the WordPress Plugin Directory that exist to be the base for anyone to create their own plugin.
There is more to learn about PHP than with HTML. However, you can do far, far more with PHP code than you can with HTML. PHP also differs from HTML when it comes to displaying pages. While HTML can be styled by using tables and adding background images as well as by CSS, Php requires a CSS Stylesheet. CSS is used to display content, set color, and layout of every page. PHP pages use the information from the CSS Stylesheet to place content on the appropriate template.
The video below will give you a good start on understanding how to create the code you will need to make your plugin work…
WordPress Plugin development – Creating a WP plugin from scratch.

Wordpress Plugin development - Creating a WP plugin from scratch.

NEW WORDPRESS PLUGIN DEVELOPMENT TUTORIAL http://www.youtube.com/watch?v=W1FWRNY4TSQ WE ARE GOING TO BE CREATING A NOTICE BAR FOR OUR BLOG. Enjoy. WordPress …

Video Rating: 4.7966104 / 5

There’s no way around the fact that writing PHP code is more complicated than HTML. There are more rules to learn and remember. Even seemingly simple tasks may require several hooks to complete. The subject may be technical in nature, but if you learn the basics your horizons are wide open.

If you have ever searched in vain for a plugin that will automate a common task or accomplish a particular mission on your blog then this is your chance to make it happen. You hardly need a degree in PHP Programming to create a WordPress plugin. Besides being a potentially profitable skill, creating a plugin and then watching it in action on your blog is quite an experience.