What is an effective website?

An effective website is one that remains true to it's objectives AND delivers on them.

The primary focus is not usually about being creative, or funny, or entertaining – it’s about motivating people to act. Creativity, humour or entertainment may of course be utilized, but only if it directly supports the action that you want your readers to make. There are many websites that completely miss this point; and created by 'top' designers too. Keep it simple. Know who your target audience is and make your messages relevant to them and their lives. Then remain focused and avoid cluttering things up with distracting and unnecessary elements.

The same can be said for developing any marketing devices.