Arun Jacob writes "The NYT has an interesting article — Using the Web to Get the Boss to Pay More — on online tools that can help in salary negotiations. Link here (Free registration required).
To summarise, the article talks about the websites that provide information on standard compensation packages for your position and role. Using this information, it should be easier to negotiate your pay with a fact-based approach rather than "feelings-based" approach. The sites profiled are —
Salary.com (Data available only for US)