You can do market research. You can study focus groups. You can try to start a Facebook group or roll your own online community. Or, if you are Robert Scoble and Seagate, you can invite your fans to meet you in Times Square for a free hard drive.
Seagate just launched the fall lineup of their FreeAgent external hard drive family. They rented space on the two biggest screens in Times Square to tell everyone about it. And they gave away a handful of drives to some of their best fans.
Traditional marketing generates average products for average people, because these products are targeted at the everyone.
From Seth Godin's talk called "Why marketing is too important to be left to the marketing department" at the Business of Software conference. Go watch the talk.