Joan and Gregory Shreve are the authors of the Sixty-Sixty blog. Their first blog post–“Why Sixty-Sixty?”–introduces who they are and explains the reason for the blog name:
In the WordPress realm Joan goes by the name “Swedish Falcon” (given to her by her son-in-law Patrick). Greg goes by the imaginative moniker “Gregory M Shreve.” Although, if you really want his attention, yell “Dr. Shreve” really loudly.