I currently subscribe to My Glam and the Look Bag (but if I win the lottery I'll join them all). Listed below are some that are available in the United States (there are many more available in Canada, Europe and Australia). There are also more available in the US, but these are pretty affordable (others available range from $20-$50ish per month or they ship quarterly...what's the fun in that?). Anyway prepare to sign up and possibly be put on a waiting list, but don't fret I was on my waiting lists for less than a month (then a bunch had openings, I picked two). I figured I'd join for a while then switch it up down the road. Enjoy!
Beauty Sample Subscription Sites available in the US:
birchbox $10 a month, brands like kiehl's, smashbox, stila
test tube quarterly program $29.95/box, brands like philosophy, ahava, garnier, olay
beauty army $12 a month, brands like korres, boo boo fix, nyx, pur~lisse
crave box $10 a month, with beauty products and products for your home, health, pets, tastebuds
ipsy (formerly myglam) $10 a month, brands like urban decay, dermstore, pur~lisse
eco emi $15 a month, eco-friendly and green items
look bag $10 a month, products like lalicious, cattiva cosmetics, rain cosmetics, laura mercier
beauty bar/sample society $15 a month, in conjunction with Allure magazine, brands like bliss, boscia, dermalogica, jemma kid
beauty box 5 $12 a month ($30/quarterly or $100/yearly) brands like weleda, supergoop, makeup geek
goode box $16 a month, brands like josie maran, coola, youngblood, 100% pure
green grab bag $15 a month, "an eco friendly bag of natural beauty products"
klutch club $18 a month (or less?) this one is more for health, wellness and fitness
beautyfix $50/quarterly (plus tax in some states), brought to you by dermstore they pick some products and you pick 8 samples (there are a lot to choose from)
soapbox $20/quarterly "hand crafted bath and body products"
subscription boxes a whole site devoted to subscription boxes (beauty included) and reviews...it's like a one stop shop! :)