For the last couple days the "visitors/day" counter displayed in Site Stats (right sidebar) shows 0
:
I think it's incorrect, we have a few questions/answers/comments/votes every day, it's simply impossible to be 0
.
This is a known bug: see Traffic (views, visits) isn't correctly registered on Site Analytics or Area 51
From this page it seems that the bug affects all Stack Exchange sites, except Stack Overflow.