Screen Sieve lets you search the contents of the currently active window at any time. It highlights all occurrences of characters, words and phrases as you type, without requiring modifications to applications. Putting Mac OS X\' built-in support for Accessibility to good use, Screen Sieve works with any application that supports the Accessibility APIs. Applications that do include Mail, Safari, Xcode and the Finder, as well as most other applications written in Cocoa and to some extent Carbon.
Screen Sieve lets you configure the hotkey used to invoke it, as well as the color used when Screen Sieve fades your screen. It can also be configured to start automatically when you log in.