Seems to be ubiquitous...the "done" or "completed" column. Conceptually what purposes does it serve? Is it the feel good reminder that "hey we've accomplished X number of tasks/stories"
I struggle with using valuable screen space or physical whiteboard for such a thing, when electronically I can pull those tasks up at any time.
Perhaps in Scrum, with it's iterations, the "done" column is handy for showing team/stakeholders/collaborators whats been done and what needs to be done and what is being done.