Not exactly the same issue as you, but I have a couple of domains in particular that get very random, sporatic traffic. One of them for instance, will average 2-3 clicks and .25 to .50 per day pretty consistently, but randomly (2 or 3 days per month) it'll get 50 to 100 clicks or more for $20-$80 or more. In fact just a couple of days ago I hit $95, and I have no clue what is going on, although i'm not going to complain. My only worry is that the parking company will think i am trying to cheat them, but so far so good, most of the clicks are from south america and indonesia.