Here are some start-ups that offer new online twists on thrift stores and yard sales:
Copious: A "social marketplace" for buying and selling through your extended social networking contacts. www.copious.com
Threadflip: Offers both do-it-yourself and concierge-type services to let users resell fashion items. www.threadflip.com
ThredUP: Online marketplace for secondhand children's clothing. www.thredup.com
Twice: Buys and photographs customer clothing, then resells on its website. www.liketwice.com
Poshmark: Users upload photos of their items, then troll virtual "Posh Party" boutiques for upscale bargains. www.poshmark.com
