Agreed about westfly.com, also, oregonflyfishingblog.com is an awesome resource.
Of course, OFFB is in the business of sellin' stuff, so they generally recommend an unnecessarily huge amount of flies (unnecessarily huge, IMO only, of course), but you can get an awesome idea of what the majority of fly fisherman are catching fish on in the area from a place that can monitor trends by sales numbers(it's the American way, YO).
I also agree with fisherwilly on the light dark idea. I tend to use light and dark EHC's for dries, and possie bugger (light) and mega prince (dark) tandems almost exclusively.