It depends on where I pull the traffic from:
when I post on social networks, like Tumblr, I usually get at most 3 concurrent at a time.
If they come from direct source they are usually more spread around the clock also due to their time zones differences.
The peak I had was when I wrote a comment on the Sex channel on Reddit right after the launch of my platform (http://www.sexycrets.com) a few months ago.