Source of Icons to help spruce up your custom entities

I like the silk ones from this series: http://www.famfamfam.com/lab/icons/

These are interesting. http://ndesign-studio.com/resources/pixel_icons.htm
Some interesting samples: http://www.icongalore.com/sales/purchase-and-download.php

Great Variety of them are also available here: http://www.iconarchive.com/