Nice thread, OP. You may already know about this, but here are a few presents for anyone who wants to find the artist/source behind any of these pics:
http://iqdb.org/Basically, a reverse image search for "anime" images; you give it a picture (upload or URL) and it tries to find it in a database of images. If you have a low-quality or lowres copy of an image, it can even sometimes find a better quality version for you (but not if the original copy sucked!)
http://danbooru.donmai.us/A *booru is basically a tagged collection of images. It's handy for finding more pics done by an artist, for finding the original source of an image (usually pixiv, which is basically a Japanese deviantart clone), and for discovering new images (very explicit details about a picture can be tagged, like the type of outfit a character is wearing, the setting, the overall color theme or mood, etc. All of these tags can be searched for). While these sites tend to contain a lot of pornography, you can always include "-rating:explicit" in your searches, which removes all pornographic content from your search.
iqdb uses a number of boorus as the databases for its searches. If you have the option, I recommend clicking on the danbooru search result, as it has the highest quality tag database that I know of. As an example of iqdb's functionality, here are danbooru pages I found (in seconds) on some of the pieces I liked from this thread (including author tags!):
http://danbooru.donmai.us/post/show/1157918http://danbooru.donmai.us/post/show/1162754http://danbooru.donmai.us/post/show/1161093http://danbooru.donmai.us/post/show/1168373 
