The mother of all reports, the All Jobs Summary offers an overview of all of your positions and some basic information about each one. There's not much data to slice and dice here, but it's a great way to get a high-level view of your company's current hiring priorities.
At a glance, this report will tell you when jobs were opened and closed, who is responsible for each part of the hiring process, and the number of candidates (old, new, and hired) on each job. If you've added any custom job fields on the Configure->Custom Options->Jobs page, you'll see them as extra columns on the right side of this report as well. Since this report has so much data, you can export to excel to slice and dice all sorts of interesting information.
How can this report be filtered?
The All Jobs Summary can be filtered by Department and Office (located right next to your company name), as well as Job.