OpenStreetMap
Here are some interesting road intersections that I have found on OSM. Have you some to add?
http://osm.org/go/euzM9Jc9 Gravelly Hill, UK
http://osm.org/go/eumbsz86y-- The Magic Roundabout, Swindon, UK (here is google version http://maps.google.com/maps?f=q&source=s_q&hl=ru&geocode=&q=The+Magic+Roundabout&sll=51.570831,-1.795988&sspn=0.054948,0.154324&ie=UTF8&hq=The+Magic+Roundabout&hnear=&ll=51.562869,-1.771502&spn=0.001717,0.004823&z=18 )
http://osm.org/go/0t2wPMaRk- Taganskaya Place, Russia
http://osm.org/go/0BPIBrSpe- Place Charles de Gaulle, France
http://osm.org/go/uNlQyvAC-- Canberra, Australia
http://osm.org/go/TYqvbSw1-- Los Angeles, California, US
http://osm.org/go/ZSAHJx73 Atlanta, Georgia, US
Discussion
Comment from bass on 9 January 2010 at 12:57
Not as impressive as yours, but still fun to drive around the peanut
http://osm.org/go/0C0XMH7DL- Glattbrugg, Switzerland
Comment from Head on 9 January 2010 at 13:34
Take a look at Kreuz Kaiserberg in Duisburg, Germany. It's also interesting to see that, just south of the intersection, the Zoo is split by the autobahn.
http://www.openstreetmap.org/?lat=51.4437&lon=6.80323&zoom=15
Comment from hkucharek on 9 January 2010 at 17:44
This on in Sydney, Australia was recently mentioned:
http://www.openstreetmap.org/?lat=-33.829894&lon=151.214222&zoom=18&layers=B000FTF
Comment from Baloo Uriza on 9 January 2010 at 19:42
http://osm.org/go/WIDPKSDKW- The Octopus (an 8-way intersection), Beaverton, Oregon
http://osm.org/go/WIDlNQKB I5 at I405 and OR43, Portland.