So in my rather passive interest in cryptography, I created a simple project and plan to soon make it available on my site as a web page. You can download the zip file of the Windows Form project here. (Requires Visual Studio 2010).
I got excited as I listened to one of my favorite podcasts: TechStuff from the How Stuff works website. It was on the German WWII cipher called the Enigma. It is of great historical interest. I had to listen to this particular episode twice to catch the name of the modified Polyalphabetic Substitution Cipher they used.
I had to look up the Vigenère cipher to understand how to decrypt messages.
The podcast also refereed to this online crypto museum of which I have not been able to thoroughly check out.