So this all makes me wonder if there is a way to create a central database about fraudulent transactions, and associated addresses.
It's nearly impossible to mark certain Bitcoins as stolen or dirty because they can be so easily laundered. For example, send the stolen coins to an account at MyBitcoin.com, withdraw the coins to a new Bitcoin address. The withdrawn coins are completely clean and other MyBitcoin.com users end up with the "dirty" coins.