A nice tool for conducting programming interviews

I have been interviewing people for developer jobs for some time now. At our company most interviews are conducted on phone because most of the candidates are located out of station. I have always found it difficult to judge a person's programming ability on phone because I think its easier to write code than to "speak" it. I recently came across a blog post on interviewing for programming jobs. It is an interesting post but I dont know how helpful it will be for me in future but there's a tool mentioned somewhere in there for conducting online coding interviews. This online tool at http://www.seemikecode.com/ seems interesting. I will try to use it for few interviews and then see how useful it really is.