Magento Color Swatch is an extension for configurable products which can show to your customers how a product looks like in different colors, patterns or designs.
Custom options or product attributes such as color, size, types can be displayed as thumbnail images. It works well with any type of products, simple products, configurable products, etc.
It does not require to hack code, or change magento core or change anything in your magento store. Also integrate the zoom feature for this extension.