Getting the right online marketing tools to do that is also very important. Some very successful websites has implemented their own personalization tools. Some large companies has invested a lot of money to implement high-end web analytics products with behavioral targeting tools like WebTrends. Coremetrics and Omniture, so those companies can make it possible to deliver dynamic content for their website visitors.
Implicit personalization is easier to implement, because you can use 3rd part tools that are Javascript based, in order to serve dynamic content to your visitors, based on segmentation and actions. It is all done via SaaS Web Analytics solutions, and even the alternative media (pictures, videos, etc) are uploaded to IDN (International Distribution Network) and served to the visitors within the application Cloud IDN solution implementation.