There are actually alot of popular skin stores! I'll name a few that I know are pretty popular.
Essences, Birdy, The Shops, Deeses, DeeTalez, Glam Affair, Modish, League and there are some others, my mind is just totally blank right now. But I know a lot of people shop at those nowadays.
And for hair:
MAG, Due, Little Bones, Leverocci (Marketplace), ISON (Marketplace), Laviere, Exile, Lelutka, Truth, Magika, D!va, Dura Girl, Eaters Coma, 69, Chemistry, Fashionably Dead, Lamb, Clawtooth, Faenzo (Marketplace), Dela just to name a few that I know are pretty popular and there are many many others ofcourse.