TEXTURES: colorfilter - Their big 40 pack of icon textures (download link at Facebook here) is still the one I use most often and I haven't begun to scratch the surface of the hundreds of textures within. Also check out the pack of larger 800x600 textures. You can also find the sets posted individually on their journal. I've posted a few more examples of my icons using these textures in the comment thread here.
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texturize - (Many thanks toteragramm for rec'ing this community) One-stop shopping for anyone interested in creating and sharing textures. Be sure to read the comm's very informative "Bible" (guidelines) before posting or snagging. Most of the artists post links back to their graphics journals or to Deviant Art.
scoobyatemysnax at burnedbreads - includes tutorials. A tremendous variety of textures including soft glow, grunge, frames, abstract and geometric patterns in any one given set. I like their medium (300pixels) square textures for icons.
SCREENCAPS for Buffyverse slayerstillness has a list of Screencap Resources for BtVS and AtS, including all the ones I use most frequently; if you know of any not on the list, send the links to starry_night. Some of my favorites from the list:
* Pretty as a Picture complete screencaps for BtVS and AtS plus promo photos for Buf (ETA: 12/21/15 site currently defunct)
* Bloodqueen has all seven seasons of BtVS complete, is one of my primary sources
* Leave Me the White by _jems_ Spuffy-centric so no S1 or S3 caps and the remaining seasons are incomplete; but some of the best quality caps of the series I've found. (S2 is the most complete with 14 episodes capped.) Includes Dailies for Smashed and Dead Things. S7 is spread out over three albums including two Miscellaneous albums.
* Shadow of Reflection also has all seven seasons; quality if variable. The early seasons caps compare favorably with Bloodqueen's; the later seasons are strangely distorted.
* Screencapped.net WiP; S1-2 of BtVS are complete; plus one file of promo shots from S1 and the screencaps for Bargaining. Appears to be using a new cleaned-up source for it's caps (the so-called "high deflnition" version.) Has a lot of screenshots that may not exist elsewhere, but can appear slightly compressed or distorted.
* The Chosen Two Gallery high-quality promotional and marketing images and magazine shoots of all the major and most of the minor characters/actors in BtVS, AtS and Firefly.
* Kiss Them Goodbye Seasons 1 - 2 complete, partial season 3; also appears to be working off newer DVD's or Blu-ray sources but the images tend to be more pixilated than other sources.
Individual Cast Members Fansite Galleries: * Sarah Michelle Gellar France - What it says on the tin. One of my favorite fansite galleries for all things SMG and constantly updated. Photoshoot albums sometimes identify the magazine and the original photographer. * Glamorous SMG - online since 2003, another fairly comprehensive source. * Captivating SMG - relatively new (since 2013), it divides the Photoshoot section by years, which few sites do. Galleries for Sarah's other tv series still incomplete or empty as of this writing.
For other fandoms: * All movie/tv caps on Leave Me The White. Extensive collection including Grease, Amelie, Dangerous Liasons, Terminator; Parks & Rec, Veronica Mars etc. * Genre Caps HQ screencaps for several fantasy series: Jessica Jones and other Marvel series, Doctor Who (New Who); OUAT, Outlander, etc
OTHER IMAGE SOURCES * The British Library offers over one million royalty-free digitized images from their vast archives going back to the 17th century. * The Brooklyn Museum of Art happens to be one of the best art museums I've ever visited. If I had to choose between a visit here and the Met, go to Brooklyn. In the meantime, their online collection has a stunning array of images. * The New York Public Library Digital Collections Thank you petzipellepingo for the heads-up! * The Graphics Fairy and the Background Fairy - the wonderful team at Graphics Fairy provide thousands of free large HQ images adapted from antique and vintage greeting cards, labels, valentines cards and assorted emphemera, DIY tutorials, craft projects, etc. * morgueFile * Archive.org * StevenJamesMorris at DeviantArt
TUTORIALS & GUIDES * good_tutorial What it says on the tin. The last post was 2013 but still plenty of useful information