Its been a couple years on my GS now, and I have found i tend to shop a couple retailers for parts, etc.
Excluding big box stores, like revzilla/cyclegear, i am curious where people shop around the world.

Stateside, i usually check out the following:

Beemerboneyard
Used parts and maint items

Sierra Bikes
They still have a few parts my older bikes like mine

Max BMW
Parts. Great parts dept too. I have spoke with them on parts for my bike a few times.

Sw Motech
Accessories

Touratech
Accessories

I will lookup parts on the motorrad site, and search elsewhere, but have had to order from there before.

I would love to know other places people go to for parts/accessories!