http://www.cherryculture.com
Selling everything from Eyeko to LA Colors to NYX to Milani to Sinful Colors, this website is packed with bargains. This site is especially good if you are looking to buy NYX products below the retail price. Something else I really appreciate about this site is that they almost always have products in stock and don't sell out like other sites tend to. I have ordered from Cherry Culture several times in the past and have always been satisfied with my purchase.
http://www.beautyticket.com
This site features more high-end products such as Tarte, Smashbox, MAC, Kiehls, YSL, etc. They have a good variety of products at any given time, although the merchandise does change according to what they have in stock. Prices are typically lower than retail and they tend to have a lot of older products (i.e. things that may have been discontinued). One of my favorite things about Beauty Ticket is their cute packaging. My orders arrived to me with pink packing inside the box that I enjoyed!
http://www.allcosmeticswholesale.com
If you are looking for discontinued high-end items, this is the website for you. Since this is a budget beauty blog and I assume most of you are not seeking high end items, All Cosmetics Wholesale does sell some discounted high end items, but you'll have to look around. Perhaps my favorite thing about All Cosmetics Wholesale is that they sell samples of authentic MAC pigments for $3.99. These pigments can be used loose, or can be pressed into pan form if you buy 2-3 samples. This is a great way to try out a MAC pigment for a fraction of the cost of a full size jar.
http://www.starsmakeuphaven.com
This website also sells MAC pigments, although I've never personally ordered from this site. They also sell a variety of empty eyeshadow pans, pots and palettes (how's that for alliteration?).
Have any websites to share? Feel free to leave a comment and let me know!