Etsy - Buy and sell handmade or vintage items, art and supplies on Etsy, the world's most vibrant handmade marketplace.
Amazon - Everything you could ever want to buy. Get a free year's subscription to Amazon Prime (free 2-day shipping!) with a .edu e-mail address. Also check out the daily Gold Box Deals.
ModCloth - Mod retro vintage clothing & indie accessories.
Craigslist - Buy and sell within your own local community. Recycle all those things you never use!
Trip Advisor - Going somewhere? Unbiased hotel reviews, photos and travel advice for hotels and vacations, all around the world.
See a list of all the deal sites you should be checking out here.
