AuctionMart seems to be an excellent application of the internet to an old problem. Seems like every Respiratory Therapy Department I ever worked in had equipment which was in disuse, but was perfectly functional. These were untapped resources, which could be easily sold to other facilities which could use them. In return the selling department can use the generated revenue to get equipment they can use. The internet enables geographically distant places to carry out these transactions.
And yes, eBay does the same thing with, say, Beanie Babies.