Don't worry; I have a testimony - let me explain what I mean by the thread title. Perhaps someone here has heard of LessWrong, self-described as "a community blog devoted to refining the art of human rationality." While much of its content comes from an atheist humanist, and indeed the concept of a testimony is considered too unlikely to be worth investigating when it's mentioned at all, but it's the best online community I know of that focuses on cognitive biases, psychological fallacies, proper statistical reasoning, etc. It's possibly the best resource on rationality, period.
What I envision is an LDS website, founded upon the premise that the Church, gospel, etc. is believed to be true, that documents and discusses Mormon-related thinking. For example, there's the philosophy of testimonies, the availability of sources for official doctrine, and the biases and fallacies that come about from incorrect understandings of church doctrine (such as black-and-white thinking and confusing doctrine with LDS culture).
What do people here think? Interesting? Badly defined? Already something like this out there?