Magento: Product image Deep Zoom Extension

http://www.magentocommerce.com/magento-connect/mygento-deepzoom.html

JQuery library for Magento

 jQuery is a cross-browser JavaScript library designed to simplify the client-side scripting of HTML

http://www.magentocommerce.com/magento-connect/utilities/developer-tools/mygento-jquery-library-and-powerful-plugins.html

Magento Custom Admin Theme

http://inchoo.net/ecommerce/magento/custom-admin-theme-in-magento/

Just create new theme and place modified files and new files only instead of all the stuff from default theme.

Magento: Free banner extensions

http://www.magentocommerce.com/magento-connect/multiple-banner-extension.html
http://www.magentocommerce.com/magento-connect/banner-slider-3912.html
http://www.magentocommerce.com/magento-connect/simple-banners.html

Magento: Programtically Cancel the coupon code on the shopping cart

$quote = Mage::getSingleton('checkout/session')->getQuote();
$oldCouponCode = $quote->getCouponCode();
if (strlen($oldCouponCode)) {
    $quote->setCouponCode('')->collectTotals()->save();
}

Delete Test data from Magento

Delete Test Products from Magento:
http://www.sonassi.com/knowledge-base/magento-kb/mass-delete-products-in-magento/


Delete Test Orders from Magento:
http://inchoo.net/ecommerce/magento/delete-test-orders-in-magento/

Magento Database Diagram and tables:
http://www.magentocommerce.com/wiki/2_-_magento_concepts_and_architecture/magento_database_diagram
http://www.magereverse.com/


Delete all products:
http://www.magentocommerce.com/boards/viewthread/20553/

Best PHP IDE

http://www.jetbrains.com/phpstorm/
http://netbeans.org/kb/docs/php/phpunit.html
http://netbeans.org/features/php/index.html