I have seen presentations in Power Point which contain a timer. Can this be done in Beamer using a simple command, or maybe a package? If not a timer, is it possible to at least get a clock on your slides?
The PDF presentation software http://impressive.sourceforge.net/ has a timer overlay. It takes any PDF file and displays the pages in sequence, with optional transitions between pages.
Once in the software, press "t" to enable and disable the timer overlay. You can control it's position by using the command line options to the program. e.g. here is my command line
impressive pres.pdf -L margin=16,time=BL --fontsize 16 --transition None
This means it'll show the file pres.pdf with the timer on bottom left (after I press "t"), make the font a bit larger, and disable any transitions.
To get a nice "presenter display" (dual monitor support, clock and timer, displaying the following slide, etc.), I have used the following solution:
Use PDF to Keynote to convert the output of Beamer into Keynote format.
Then simply use Keynote to give the presentation.
Works very well in practice; quick and easy. Of course this approach requires Mac OS X.