One of my favorite plugins in the entire world is Widget Logic.  It gives you the power of Conditional Tags to pinpoint what areas you want a widget to show up. It saves you from having to use multiple sidebars (I’ve had websites before this with as many as 10!) and allows you to easily move your sidebar content around.

You can see it in action on the Social Media Clubhouse website – the various events have various images, logos, and link categories showing up depending on where you are on the site.

You can download the plugin from the official WordPress repository, or install it through your local blog!

EDIT: Screencast below