Quicksilver is a launcher utility app for Mac OS X which gives you the ability to perform common, every-day tasks rapidly and without thought. An introduction to Quicksilver's abilities include:

• Accessing applications, documents, contacts, music and much, much more.
• Browsing your Mac's filesystem elegantly using keywords and 'fuzzy' matching.
• Managing content through drag and drop, or grabbing selected content directly.
• Interacting with installed applications through plugins.

For example, if you want to launch an application hidden in the depths of your file system, simply activate Quicksilver with a keystroke, type a few letters of the application's name, then hit Return or Enter to launch it. When you don't need Quicksilver, it keeps out of your way, preserving precious screen real estate, and yet you can summon it instantly with a key stroke - just like Mercury the winged messenger. (Ed. Note: Actually, Roman mythological texts are remarkably silent on whether Mercury could be summoned with a key stroke, but it would have been great if he could. Quicksilver will certainly make you feel as if you have god-like powers.) Read more.