theyrule.net – interlocking boards
theyrule.net is an online tool where you can map and visualize board interlocks. You can look up specific people or simply play around and click to see various interlocks. Or just use the “auto”-mode and watch. I don’t know how up-to-date the site is, but it is definitely fun/interesting to play around with.
Of course, there is a long history of research on board interlocks.