DTCPathView by DanielToddCurrie - Line of Sight Software http://los.dtcurrie.net
DTCPathView is an open source class that can be used freely by any Cocoa/Objective-C developers. It allows the programmer to easily add auto-completion of absolute path strings to any NSTextField.
DTCPathView requires Mac OS X v10.1 or greater. The class source also comes with an example project which requires Xcode.
Visit the Line of Sight website for more details, or download the source here: http://www.columbia.edu/~dtc21/DTCPathView1-0.dmg.bin