Sam,
Who suggested this to you? An agent or someone else?
On the flip side of what Nick said (luv ya Nick!), if it was suggested that you talk to them (them meaning an agent) about an exclusive contract, it could also mean that you talk to the agent about an exclusive contract in which they will only bring you their short sale listings, not necessarily the agent requesting the exclusive contract.
The Buyer-Broker agreement is different. The Buyer-Broker agreement is an agreement between you as a buyer and your agent in which you agree to solely use their services to purchase property(ies) for a specific timeframe. If by chance you use another agent during the agreed upon timeframe, you are still obligated to pay a commission to the agent you had the agreement with.
I do not ask my clients to sign such an agreement, and I wouldn't suggest anyone do so. I'm sure other agents will be upset with me for saying so, but I prefer doing business with those who work with me by freewill, not by contractual obligation.