This is a list of every -tan and -chan that I came across in the 4chan /b/ 2006-2008 archive.
Nevada-tan/-chan - A twelve-year-old girl who slashed the throat of her classmate with a box cutter. She is called Nevada-tan because she wore a Nevada sweater in a class photo and received a cult following online. First known reference here.
Rabbit-chan - Woman with flat chest. First name thought to be Caitlin. There were many threads made about her and she was referenced a lot in many threads during early-mid 2006. In one thread it was stated that there was ".zip of rabbit chan pics". She was once even said to be the "heart and soul" of /b/, but also "worse than Desu" in the same thread. In a few threads the text "RABBIT-CHAN FLOOD 8 O'CLOCK SHARP. BE THERE OR BE SQUARE" began circulating, signaling that rabbit-chan may have also been a flood. A list of all threads about her is available here. A small collection of images of her is here.
:3chan - Very Cute.
Hermione-chan - Mina Suvari from American Beauty, who happened to look like Emma Watson with heavy makeup.
Jappy-chan -
Flat-chan - Flat chest.
Loli-chan - Loli, obviously. Said to be important to 4chan.
Magic-chan - Apparently looks very geeky. Disliked by majority of /b/, worshipped by a few people. Said to actually a fat man pretending to be a girl on the internet, but this is unconfirmed. Anothr said more specifically she was a fat man "rolled up in black twine". It was also once said that her teeth were disgusting. Original thread here.
Neko-kun - Presumably a cat/furry boy.
Togi-chan - A woman with a large ass. A collection of images of her is here.
Boatlights-chan - Another name for Suiseiseki (desu) (actually its Souseiseki but /b/ is dyslexic). First appearance here.
Pete/Ron-chan - Some Ginger guy. The first thread he made that made him known on /b/ is here (and a screenshot of the thread showing what he actually looks like is here). He posted my MySpace (no longer active) and other information about himself in the thread, saying that he has a firecrotch. He was first called Ron-chan because of his close complexion to Ron Weasley and Pete-chan since he looks similar to the characters from Pete & Pete. Both voting and fighting took place in the replies as to which of these was the best name, both by the end of the thread the score was tied. He is liked on /b/, most seeing him and his hats as cute.
Desu-chan - Not actually referring to Suiseiseki. Is apparently a cute guy ("He is cute, that's why we call him desu-chan."). Is said to look like "the original Nice Work guy", an old meme that there is little information about. [This is not to be confused with Desuchan, a 4chan rival that has its main focus on Desu-related memes.]
Jew-chan - Female. Unknown if actually jewish. Not much is known about her, most information is derived from this post here: "Why Jew-chan is called so? I don't see anything Jew-looking about her. :\". Only one image edit of her is thought to have survived, retrieved from Macrochan: this one.
Emo-chan - This name has been passed around several people over the years. The first known one, however, is in this thread, showing a girl with scars on her body. Many of those who replied thought she was hot, while others thought she was stupid for doing it. At one point mistaken (possibly jokingly) for Rabbit-chan.
