WordPress 2.7 Keyboard Shortcuts in the WordPress Codex is a nice page to figure out the neat little tricks to make your job of administering a blog easier and more user friendly. WordPress 2.7 adds the ability to use keyboard shortcuts to browse and moderate comments. These keyboard shortcuts are designed to save time by allowing you to rapidly navigate and perform actions on comments. If your blog receives a lot of comments for moderation and/or spam, these shortcuts might come handy.
Speaking of new features added to WordPress 2.7, Demetris has written a post on the Ten New Features in WordPress 2.7 that strikes him as the most useful. I really like his illustrated style of writing. It is worthy of note that some of the features he mentions are dependant on compatibility with your theme.