Y'know, the only time I've ever found it worth it to camp out before a big sale was when the REI flagship store in Seattle has its Garage Sales. Back in the day, it was just once a year... probably more often these days, but I wouldn't be surprised if people still camp out now.
When I was in college, we staked out our tents pretty early the night before, all around the store on the sidewalks (it was packed). And believe me, camping out for an REI sale was an entirely apropos activity.
There was a kind of circus atmosphere to the whole thing, and it was pretty orderly once the doors opened... they only allowed a certain number of members in at each time (oh yeah, you had to be a member to even go in to the sale), so you just bided your time according to what time you set up camp.
Of course, everything was used/returned/floor models, but man I got some nice deals back then. $100 climbing shoes for $10 was probably the best I did. $70 Thermarest for $30 wasn't bad, either. Now THAT was worth camping out for.
Of course, we were also on the crew team, waking up at 4:30am anyway... so "all night" was really just half the night.