Get Other Offers

Researching data points is helpful when constructing a negotiation argument, but the best argument you have is an offer in hand from a comparable company.

The big mistake most tech workers make is to be reactive with recruiters. If you decide to interview with a company, figure out comparable companies and apply to them as well. (Google and a seed-stage startup are not comparable.)

Talking to many recruiters and companies at once is painful, but it's better to concentrate the pain in a short window, rather than spreading it across several months. You can also negotiate interview dates, though this is admittedly harder in a bad economy.

As soon as you have a verbal offer, push all your other loops to skip you to onsite using that as leverage ("Don't let the awesome candidate of me get away!").