From Second Life Wiki
Neko means cat in Japanese, and in the physical world, it's not uncommon to see young teens in Japan dressing up "Neko" as a form of cosplay, inspired by Japanese manga and anime.
Within the boundaries of Second Life, a similar "virtual neko" phenomenon has occurred.
Nekos in Second Life are essentially human avatars who wear cat ears and a tail. A few have chosen to look more feral by wearing feline-colored skins, paw feet, or whiskers, but even in this form, they remain distinctly human, without the bulky masks or body shapes typically seen in the furry community.
To learn more about the history of Neko and find out how to be a Neko in Second Life, visit Virtual Neko in Second Life, a blog dedicated providing a central resource for the SL Neko community, featuring Neko resource pages, store lists, Neko "how to" guides, clothing and fashion, clubs, events, and sales.