How Can We Use Data Better?

This subject has been a hot-button issue for me for some time, so thought I'd throw it out there in a big way. The current Fast Takes (68) features a discussion on this topic. I'd love your thoughts. How are we going wrong in the use of data to target our direct marketing (including contextual banners, videos, emails, landing sites, mail programs, etc.) and what should we do to improve it? Is the mountain of data just too much to manage effectively, forcing us to work with aggregates, or is true one-to-one marketing possible even at large scales?