In many of the seminars I give on search engines and legal research, I point out that it is a mistake to rely on only one search engine, because the overlap between the various search engines is not that great. Now there’s a way to see that for yourself, graphically.Thumbshots is a ranking comparison tool that shows you the overlap between two search engines on a specific query. Just enter a similar query and any one of seven search engines, and you’ll get a graphical depiction of the overlap. Chris Sherman has more on this.
The Thumbshots page is pretty cool — my only concern with it is that it uses AllTheWeb and AltaVista as comparison tools, and they aren’t being indexed anymore — are they? If so, they aren’t very good standards of measurement.