Zuneta - Great for hard to find brand's like Rouge Bunny Rouge, Edward Bess and Hourglass.
Cultbeauty - Again, great for hard to find/more unusual brands.
Escentual - A fantastic site for French skincare brands and cheap Clarins. Super quick postage, too and the blog's fantastic!
Naturismo - Great for natural and organic skincare and cosmetics. Plus, the site offer quite a large range of sample sizes of skincare and make-up that you can buy, and worldwide postage is free.
Beautybay - Where I go to get my Le Metier de Beaute fix.
Salon Skincare - Great for brand's like Peter Thomas Roth and Alpha-H. I've picked up some fab Becca bargains in the sale section before, too.
Achica - Fab for pretty and unusual home accessories and furniture. There's always a nice range of trinkets on offer, and I've picked up some lovely, reasonably priced cushions, prints and bedding in the past.