For the past few years, I've purchased an Ipsy subscription for my mother every Mother's Day and it's her favorite way to try new makeup. At only $10 per month (or less if you buy the whole year at once), you get a makeup bag and five "deluxe" samples, some of which are oftenn full-size products. I received it myself one year and found it to be a lot of fun, but I just didn't need that much makeup sent to my house each month. They also have great deals, like full-size roll-on perfumes for $8, for subscribers.
My sister swears by Birchbox, which is also $10 per month with five products to sample. It comes in a box and includes more skin care items than Ipsy but also features makeup. I think both subscriptions are great for people who want to try high-end products (and sometimes not as high-end) without spending money for the full price. It's also fun for people who like to try out new colors, but if you are pretty particular about what you like (ahem, like me) it might not benefit you as much.
Which makeup subscriptions or deals do you use? Which saves you the most money?