Seth Roberts has unexpectedly passed away. Others who knew him more intimately than I did, have already penned, quite eloquently, why he will be missed. See John, Tucker, Ryan, and Richard.
I only want to add, that in our emails and Skype chats and our occasional meeting in meat-space, what I admired most about Seth was his ability to explore, defend and test interesting, and often unpopular ideas (and even people) – the hallmark of a bonafide truth-seeker.