The Admin Menu module is one of the first contributed modules I install whenever I set up a Drupal site. I don't know how I ever lived without it.
It adds a simple, small (but complete!) set of menus to the top of each page in your site - visible only to administrators (or whichever roles you've given permission). It makes it incredibly easy to add new content, check your logs, and update module settings.
Unlike some menu modules, it's very responsive - downright zippy, in fact.
One of the best things about it is the way it lets you see what all your administrative options are, all in one place. If you're not sure where to go to complete a particular task (say, updating your Imagecache settings), you can find out at a glance just by hovering over the menus.
It's wonderfully convenient, and it makes all the little updating and administrative tasks faster and easier to manage.