This is a custom sidebar. Continuum gives you lots of custom sidebar possibilities. You can use the Continuum Theme Options page to specify which pages have a unique sidebar. Or, you can use the same sidebar for all of your pages using the Sidebar Default widget panel. If you do specify that you want a unique sidebar for an area of your site, such as the Search page, you can use the corresponding built-in Sidebar Search widget panel.
In fact, Continuum comes standard with 19 unique sidebars. Wow, we're starting to sound like a car commercial, so we'll add that you don't have to use all of them if you don't want. Continuum harnesses the power of absolute customization while at the same time having a quality of meekness: you can forget about all the settings and get yourself up and running in no time flat.