Family beach photos!
In a work setting, I could see Plaxo being used to share contact info, calendars for scheduling and tasks/notes for projects.
However, Plaxo is not something I would use. To be honest I am not much of a social networking person and while I like to try new web sites and services, I rarely continue using them. One service I do continue to use and would recommend is google. They also have a great calendar program!
EDIT
MDLearning Link: http://marylandlearning.wordpress.com/2008/09/22/thing-2-plaxo/#comment-78
