Threadflip
How it works: You can upload a pic of the item you want to sell with the click of a button through the Threadflip app (or on your computer), fill in a simple form and bam! your designer or vintage item is listed in an easy-to-use, boutique-like setting. When a buyer purchases an item, Threadflip emails the seller a prepaid USPS shipping label. Once the buyer receives the item, the seller’s account is credited after a five day satisfaction period. The seller can cash out the money or use the funds towards future purchases on Threadflip.

If it all seems like too much effort, you can also apply for their new White Glove Service, through which you get a prepaid box to send them a bunch of clothes in; they select, price and list your items in their Editor’s Picks closet and you receive 60% of the total for items that sell.
Pros: The content is good and the site feels friendly, smart, personal and easy to use.
Cons: There’s a 20% fee for selling–though, this is comparable to competitors.