If you haven't checked it out yet, I highly recommend you spend some time exploring episcura for their hdri textrue and reference photo library, Not only do the images look great and tileable but the layout and organization is phenomenal. They are continually adding new content and it looks like they even take requests via facebook and twitter!
Membership comes in three flavors from "Free" to "Pro"(1GB a week) " to "Premium"(2.5 GB a week) .
Go check it out !
episcura.com was born out of necessity. Textures available at stock sites are not affordable. HDR images are very expensive. A few CG artists decided to rectify the situation and created this new resource.
Our new home for seamless textures also offers HDRI and snapshots. The snapshots can be used to pitch ideas to clients, as references for models, or whatever you like. The textures and images are royalty-free.
Speaking of free, you can download 15MB daily for free. Monthly subscriptions are available which give users more download bandwidth. The site just launched and future plans include a free page that doesn't count against your bandwidth, 16 bit plates and a contest with a cash prize.
New images are added weekly and the team is eager to get some feedback. Contact us through twitter or Facebook. Let us know what you'd like to see!