Magento important links

Magento tutorials
For beginners
http://tutorialmagento.com/magento-tutorial-for-beginners

for developers
http://tutorialmagento.com/magento-tutorial-for-developer
http://leveluptuts.com/tutorials/magento-community-tutorials

• How to add upload field to contact form and send as attachment in Magento
• How to secure Magento shopping cart with https 

Rendering and filtering

http://stackoverflow.com/questions/20485525/magento-custom-column-in-adminhtml-product-grid-which-contains-custom-output-l

http://www.atwix.com/magento/grid-filter-for-columns/