Prime links
http://io9.com/5819325/the-bizarre-mathematical-conundrum-of-ulams-spiral
http://scienceblogs.com/goodmath/2010/06/the_surprises_never_eend_the_u.php
http://img529.imageshack.us/img529/615/ulam3.png
http://imprompt.us/2010/ulam-spiral-take-2/
http://home.manhattan.edu/~peter.boothe/ulam.pdf
http://mathworld.wolfram.com/PrimeSpiral.html
http://blog.morphism.com/2010/05/building-numbers.html
http://blog.morphism.com/2010/07/pdfs-from-building-numbers.html
http://math.ucr.edu/home/baez/roots/
http://math.ucr.edu/home/baez/roots/polynomialrootssmall.png
http://incubator.quasimondo.com/flash/wheel_of_primes.php
http://incubator.quasimondo.com/flash/Primeverse_1024.html
http://rob.tarrfamily.com/share/Triangle.gif
http://www.numberspiral.com/p/p006.html
http://www.numberspiral.com/p/common_diff.html
http://punarvak.blogspot.com/2010/07/ulam-spirals-and-its-variants.html
btw, via the last link I came across to the very interesting “On-Line Encyclopedia of Integer Sequences” http://oeis.org/Seis.html (a service of http://oeisf.org/). Their search facility allows you to enter a series of numbers separated by space or comma and check if they exist in some known integer number series.