Workbench is a new feature implemented in Drupal 7 to help people manage the content they are responsible for.
When you log in, you will see a reference to My Workbench in the admin bar. If you click on that, you will see two main sections here. The first is a list of the pieces of content you personally have most recently edited. The second is all Recent Content in My Sites, which will list all content in any sites you have permission to edit, in order of which were most recently edited. You can sort either of those lists by the titles of the columns you will see there. You can also view all of the content in both sections.
This will be a great place to keep yourself organized, especially if you’re looking for content you can’t easily find by navigating the site.