Here are a few of the real gems I've found on the net:
Carl Roper's "Evolution of a N Gauge - 3x5 layout", a nice introduction to basic construction and realistic operation of a small, portable layout. http://users.iafrica.com/c/ca/caroper/tutorial/
Carl Arendt's "Micro / Small Layouts", a wonderful collection of big ideas for small layouts. Dawson Station has been featured there more than once! http://www.carendt.com/
Adrian Wymann's "Model Railway Shunting Puzzles", everything you needed to know about railroad puzzles. http://www.wymann.info/ShuntingPuzzles/
Stephan Besier's Whitee River and Southern, an beautiful HO layout based on the Willamette Valley, but located in Europe! http://wolfram-mohr.de/besier/
N-Scale Supply, after my local hobby shop, my favorite model supplier. http://www.nscalesupply.com/
Hull-Oakes photos and reference drawings, courtesy of my uncle, Sam.
Internet Inglenook Version on which I spend many hours before building my own (works in IE or Chrome, but not FF). http://www.precisionlabels.com/shunt/jpage310.html