@Dario Western is trying to bring back Skinbook. This might be a bit more what you are looking for. To my own knowledge, there really isn't a current site with a chat session. At least none that appear very active or that have a relative age range like IYNO has. SimplyNudist, True, and Nudistpassions do have some, but yah, not very active, and like, 50+ year old people the few times I've seen them active. If you come across something though with IYNO age range, be sure to let me know.