Sentinel is a Mac OS X application which faciliates monitoring and observing command output. By allowing the process output to be monitored with periodic execution, it becomes easy to observe changes over time. In a way, Sentinel is similar to the "watch" command line program, but includes additional features, such as diff-ing output with previous output and colouring lines of output that have changed.
What's new in Sentinel
Version 1.1: History panel for retroactively examining command output in previous iterations