Sometimes genius hits with the simplest of tools. Sometimes our customers have a sudden and steep change in their search engine rankings. The first thing we do is immediately check other client rankings to see whether or not the change appeared to be universal or a local issue. SERPs is already a brilliant, inexpensive tracking tool for search rankings and analytics data. They've now added a beautiful page that simply shows how the search engines have reacted across thousands of sites they are monitoring.
Now, if your ranking has changed substantially on Google or Bing, you can just go visit SERPS volatility index page to see how the search engines impacted their sites to validate whether it's a local issue or whether it may have been a universal algorithm change. Great tool!