Can You Negotiate a Low-Ball Salary Offer in This Economy?

In such a precarious economy, you'd be crazy to try to negotiate a salary offer, right? After all, shouldn't you be happy to get an offer at all, even if that offer is clearly below your competitive market value? And if you don't have any other prospects lined up, what bargaining power do you really have? The word seems to be spreading that low-ball salary offers are just a reality of today's tough job market -- take it or leave it. But is this really the case or is this just hype?