Nominari has announced presenterCue for Mac OS X. It’s a free (well, sorta) app that lets the user input a list of speakers, then show them their remaining time on multiple displays as they speak.
Designed as a server/client system, its digital timer and color-coded prompter outputs to large LCDs, downstage monitors, prompter displays, and switching systems. The server can feed clients on a LAN, including iOS and OS X devices. .
presenterCue requires OS X 10.8 or later and is available worldwide exclusively through the Mac App Store in the Productivity category (http://tinyurl.com/lycf6gy). A license, which allows the server to connect with a client, is available directly from Nominari (www.nominari.com).