Payment Gateway Integration for Paypal, Google Checkout, CCAvenue for several sites.
Helped prevent SQL Injection and Cross-site scripting in several sites.
Shopping Cart development and Order Management system for a few sites
AJAX integration to code could be integrated in the projects
Image manipulation, like auto thumbnail creation and water-marking of images done for a few websites.
RSS Feeds and XML integration was done for a few sites.
Content Management Systems could be integrated.
Youtube clone was created for a site.
Have worked with a few online payment tracking and virtual money card sites