Some good online auction sites are eBay, Listia, ShopGoodwill and uBid. One of the most well known auction sites is eBay, which is good when looking for unique or vintage items, since there are many items to choose from. This auction site also has a Buy Now option.
Online auctions at ShopGoodwill are provided by the non-profit Goodwill organization. The sales help the organization provide money for people with disabilities. Items auctioned off include clothing, sports equipment, electronics and home goods.
Listia uses credits with most of the items not costing any money. Someone who has an item they don't want lists the item on Listia and waits for someone to use credits they got from people who referred them.