So, wouldn't it be nice to let them see what keys/mouse buttons that you press ... well in that case, you should give a try for Key Status Monitor.
Applications like these can be quite handy since they let you teach your users about keyboard shortcuts, etc while doing your "thing" with the podcast :). So, if your audience consist of newbies mostly, then from an educational point of view... again Key-Mon is a pretty useful tool.
It has few built in themes which you can choose + the keyboard buttons and the mouse sizes can also be changed as well. There are no scale limits, so you can make it look bigger according to your preferences.
Few other main features...
*. Scroll wheel support.
*. "Windows" key support.
*. Can represent all three mouse buttons.
*. Tablet PC touch screen support.
*. Show key combinations.
*. Add border around the on screen keys.
*. Swap left/right mouse buttons.
*. Multiple mouses or Keyboards are supported... again, these are just a few of Key-Mon's features to mention.
If you use Debian or Ubuntu 11.04 Natty Narwhal (should work for the older versions - 10.10/10.04, I think :) ) then please download the .deb package from here. Double click on your downloaded file and follow the on screen instructions.
If however, that method does not work for you, then download the .zip package from here and extract the content. Then locate the file name called "key-mon" (in the "src" folder), simply double clicking should resolve most of your "errors" concerning the above method. Good luck.