Custom channels is a very useful feature for Google AdSense publishers where they can track their AdSense performance by assigning ad units to channels based on their unique criteria such as colors, formats, or placements.

A sample implementation is to create a channel for each ad position, and see which one performs best. In the case of TechRecipes, you can create channels such as techrecipes.net-top and techrecipes.net-bottom. You can also create channels such as color-red and color-blue and then use a custom script to rotate ads using the colors to see which one gets higher CTR.