Trading Desk
  
See: Trader.
Where the action happens if you're a trader in the financial markets. It's like the sports book to a gambler, or a blood drive van for a vampire.
Trading desks provide a place for the actual buying and selling of financial instruments to take place. They plug into the exchanges, facilitating and executing trades.
They can cover any market; equities are probably the most famous, but there are trading desks for fixed income, currencies, commodities, and futures as well.