I needed to create a self signed cert to test my WCF service with username authentication in my dev environment (if you need help with this, I recommend http://www.devatwork.nl/2007/05/wcf-username-authentication/). Tried using Windows makecert cmd utility but it was give me problems. So I found a nifty tool from pluralsite called self-cert (http://www.pluralsight-training.net/community/blogs/keith/archive/2009/01/22/create-self-signed-x-509-certificates-in-a-flash-with-self-cert.aspx). It has a simple intuitive UI and works like a charm. But don’t forget to run it as an administrator.