Add sidebar creation option to the 2011 theme

How to Use Custom Sidebars on Posts and Pages | Wptuts+
This tutorial shows step by step how to add a theme option setting to add your own sidebars to a theme and then be able to apply them from the Page editor.  This is much more streamlined than having to a create a separate page template every time you want a page to have a different sidebar.

Removing specific HTML tags with Regular Expressions

matches start tag of specific tag including attributes

<\s*span.*?>

The above expression can be very helpful to strip out unwanted <span> tags.

via: Regular Expressions to strip HTML tags - www.pagecolumn.com

Use variable headers in Wordpress with conditional tags

Conditional Tags (snippet 2) « WordPress Codex
>> See snippet #3 for instructions.
"This is useful for setting variables specific to different sections of a web site, so a different banner image, or a different heading."

Conditional Tags « WordPress Codex

Learning PHP

Ending lines
Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.

Comments
In PHP, we use // to make a single-line comment or /* and */ to make a large comment block.

Variables
When a variable is declared, it can be used over and over again in your script.

Rules for creating variables
A variable name must start with a letter or an underscore "_"

A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)


Learning on W3Schools' PHP Tutorial