Glance at the price chart below. What stock is that? Hint: the exchange is not NYSE or NASDAQ, and the ticker symbol is AROD (not the delisted American Products Inc.)
The answer is "Alex Rodriguez - 1994 SP PSA Shares". The market is called ThePit.com - it's an electronic exchange for sports cards.
It differs from Ebay, which has the same cards traded, by standardizing the product and providing market making services for participants to be able to buy or sell collectable cards. Rather than searching through hundreds of offerings on eBay, unsure of the product quality or the seller/buyer reliability, you deal with a market maker. This allows collectors as well as sports "speculators" to be active in the market and provides for price discovery and market transparency (to the extent it is possible in sports cards). One can quickly get a feel for both sides of the market. This is particularly great for sellers who may not wish to have a "seller account" on Ebay and want liquidity in cards they hold. And if the price is "off", it can be arbitraged on Ebay or on other auction based "exchanges".
In order to maintain this market making service, ThePit.com runs it's own inventory, as opposed to Ebay that simply "introduces" buyers and sellers for each card. As poor as liquidity is at ThePit.com, it improves on what's available on Ebay. This relatively small market is a great analogy for the securities industry and provides a demonstration of the difference between market makers and brokers.
By the way, A-Rod has really been taking it on the chin lately...