Widgets are certainly one of the best features in wordpress. It is all customizable and it is so easy to use. It all started with vertical sidebars but i believe all-widget themes will be so popular with the release of wordpress 3.0 which brings user navigation menus to the wordpress widgets.
Since 2.8, WordPress allows us to use widgets in our templates. This made creating websites easier as well as creating professional themes. Now we can use any widget in our headers, footers or our page templates even if we don’t have a sidebar there.