These are some tools I've put together to help myself. Feel free to use them, too!

Code Quality Validator (+ bookmarklet)
Allows you to check a page for valid (X)HTML, CSS, and WAVE for accessibility--all in one shot.
github profile
My github projects:
Form Processing scripts
PHP/JavaScript to validate form data and send to email, delimited file, or other destinations.
MDaemon XSL Conversion
Some XSL transformations to convert MDaemon XML files for import into another mail system (tested most with Google Apps)
acalog to XML
PHP script to get acatalog (an online college catalog system) information as an XML file for use in CMS, etc.