Image into Sidebar
It's just an image and it's just a sidebar. The trouble is that the widgets (the content ares that populate sidebars) don't have much as far as design or layout tools. So what do I usually do?
WordPress Gallery
The built-in WordPress gallery can do quite a nice job of showing off photos. With a few tweaks, it can become a full-fledged gallery manager.
WordPress Tutorial: Simple Image Gallery with Captions
We wanted to get some images into WordPress side by side and with captions, but also in categories on the same page.