This one will be a "sticky," so it will always be easy to find. We can all add our favorite -- or the most useful -- links, etc.
This site just added our own www.polyamory.com
to their excellent list of online resources (at my request).:
I'll add internal links to the other threads which count as resources pages.
Polyamory Books, Magazines, Web Sites:
A very good list of poly resources from www.poly-nyc.com
Polyamory News Sources: