Roger Olsen is most "famous" for writing the book Arminian Theology: Myths and Realities. I highly recommend the book if you want to better understand what Arminianism really is, because it has been horribly misrepresented on the internet, much to my chagrin.
Dr. Olsen is also a member of SEA, as am I, and I have talked with him a number of times. He is a great guy, very slow to anger, and very knowledgeable on both historical and biblical theology.
Recently, over at Wesleyan Arminian, Kevin left this audio link to a fantastic conversation between Dr. Olsen and two Calvinists. What I love most about Dr. Olsen is how much I agree with him. Indeed, my only regret is by the time I read his book, I agreed with him too much to learn anything by it (though it is full of fantastic quotes). If you are curious about Arminianism, or have been shocked about some of the things that I have said about it, then I highly recommend listening to this audio and picking up Dr. Olsen's book.