I have a site that I have done little with, it is about 5 years old, and provides a free ads service. Based on Google Analytics, up until Monday 4 July it was average around 900 visits a day, then on Tuesday 5th July it shot up to 2,500 visits in one day - about 80% of this is comming from Google search. At the same time the bounce rate shot up from around 30% to 70%. On 6 July the traffic came back down to 950, a little above the average, and bounce fell back to 40% It seems that G has made some major serp algo changes for UK on or around 5 July 2011. As the bounce rate has shot up it suggests that the algo changes are not as effective, it will be nteresting to see what happens in the next few days and if there are any more sudden changes to Google. Has anyone else seen changes?
The traffic came from google.co.uk ... a huge increase in search referrals on 5 July. G definitely running some experiments. This site has no SEO done on it, it just has content added (new adverts) each day, but these are at the normal rate. The site has quite high content, site: command shows over 4000 pages.