OS X Timer with counting money app
The best "free"solution I found is the Cash Clock, allowing you to set the $ amount per hour or minute or second.

I was slightly on the high earnings site just to show the effect, but if you do make $3600 per hour let me know what job is it.



You can download it from here to run it offline, or just let it run in they web site.


  www.online-stopwatch.com is letting you download our cool stopwatch
  and countdown timers for free!
  
  This will let you use the stopwatch when you are not on the internet.
  You may have to download a new version from time to time though, as
  updates and tweaks are made.
  
  These files do not need installing! They will just run from anywhere
  on your PC. AND they will all work full screen.


Requirements:

All of our stopwatches/countdowns require Adobe Flash Player to work on your desktop. 

http://fpdownload.macromedia.com/pub/flashplayer/updaters/15/flashplayer_15_sa.dmg

The code is:

&lt;param name="movie" value="http://www.online-stopwatch.com/swf/cash-clock.swf"&gt;&lt;param name="quality" value="high"&gt;&lt;param name="menu" value="true"&gt;&lt;embed width="400" height="220" src="http://www.online-stopwatch.com/swf/cash-clock.swf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash"&gt;&lt;/embed&gt; &lt;br&gt; &lt;b&gt;&lt;font size='2' color='#000000'&gt;Get a Stopwatch like this or make your own! At: &lt;a title="Online Stopwatch" href="http://www.online-stopwatch.com"&gt;Online Stopwatch&lt;/a&gt;&lt;/font&gt;&lt;/b&gt;