Anyone tried searching google for a keyword and just keep pressing search and watch how the ads change? Quite cool. Sometimes its just the desc that changes then after some searches the positions change.
I tried that a few times looking for an ad that I was saw, but it never came up again. But I wouldn't be doing that on a regular basis, as that will inflate impressions and leave advertisers paying $5 for low CTR...(adwords still doing that?)