Transits of Venus and Mercury.
http://www.transitofvenus.info
NOAA GOES-12 X-ray Image.
http://www.sec.noaa.gov/sxi/SXI_Venus_Transit.JPG
Glenn Schneider's stereograms from TRACE imagery of the Venus transit. See the transit in "3D":
http://nicmosis.as.arizona.edu:8000/ECLIPSE_WEB/TRANSIT_04/TRACE/VENUS_3D/TRACE_3D.html Chuck Bueter's site
http://transitofvenus.org/
NASA's Transit of Venus Homepage, maintained by Fred Espenak and Jay Anderson
http://sunearth.gsfc.nasa.gov/eclipse/transit/TV2004.html
Africlipse website
http://www.eclipse.za.net/html/tov.html
European Southern Observatory site
http://www.vt-2004.org/
European Southern Observatory's Education and Public Outreach Group site
http://www.eso.org/outreach/press-rel/pr-2004/pr-03-04.html
NASA's Sun Earth Day site 2004 Venus transit site
http://sunearth.gsfc.nasa.gov/sunearthday/2004/index_vthome.htm
IAU Colloquium on the transit of Venus, at the original venue
http://www.transit-of-venus.org.uk/
Fred Espenak's site
http://sunearth.gsfc.nasa.gov/eclipse/transit/venus0412.html/
Jay Anderson's Weather site, at the Prairie Storm Prediction Centre
http://home.cc.umanitoba.ca/~jander/
Transit of Venus tours
http://www.vtransit.com/vt/index.asp
IOTA (The International Occultation Timing Association)
http://www.lunar-occultations.com/iota/2004venus/2004venus.htm
David Sellers explanations, links, and references
http://www.dsellers.demon.co.uk/venus/ven_ch_frames.htm
Rob van Gent (University of Utrecht)'s site
http://www.phys.uu.nl/~vgent/venus/venustransitbib.htm
Richard Monk's website
http://homepage.ntlworld.com/rimonk/index.htm
Historical references from Chuck Beuter at transitofvenus.org
http://www.transitofvenus.org
Museum of History of Science at Oxford Reconstruction of 18th-century Simulation
The Museum of History of Science at Oxford, as part an exhibition, showed the 18-century simulation of the transit of Venus made by Benjamin Martin, a maker of scientific devices discussed in many places, including "Fire in the Sky: Comets and Meteors, the Decisive Centuries, in British Art and Science" by R. J. M. Olson and J. M. Pasachoff.
Their Website, http://www.mhs.ox.ac.uk/venus/html/reconstruction.htm, shows three movies of the device in operation.