Most of the gfx sites have resource section which provide render packs, fractals, c4ds, backgrounds and such.
If you still can't find what you're looking for, you're more than welcome to join dA groups and take resources from there and also be notified for any new art that may be commited in the near future.
It aint dead, people in there have different time zones therefore you won't see much people online or get delayed replies at your topic.
As about gfxresource site, i agree with FG. Unless you are a pro and got some reputation you won't get any attention and it's also low activity with ignorant bit.ches.
On the other hand, people on pimped-pixels dont give a f*ck if you're queen of england or David Beckham. You'll be treated the same as the rest.