caveman - 7:25 pm on Feb 11, 2009 (gmt 0)

Some immediate thoughts come to mind just based on things I've seen:

A) Technical issues. Come at the site and sign-up/conversion as many ways as you can think of, as though you were different users, just to make sure there are no technical issues. Seems stupid but can't tell you how many times I've seen that be the problem. Sometimes it's only what some users do in some particular sequence or whatever, like a form doesn't get passed if some field is filled out a certain way that is common but was never checked/verified.

B) Conversion norms. Are you certain that the conversion you are seeing is way below the norm for this vertical/niche (there's wide variation across verticals). Do you know what it "should" be?

C) Audience/offer disconnect. There is a disconnect between the users' mindset/needs, and what the page seems to offer once they land there from a search engine (i.e., getting traffic doesn't always mean getting the right traffic)

D) Conversion strategy/tactics. Is the page/process is poorly designed with respect to conversion. Number of steps in the process, nature of "call to action", offer value, size of buttons, placement of sales information and action elements on the page, even colors and graphics.

May be some combination of the above. In your shoes I'd be sure I've investigated all of the above. If that doesn't work, find some people who might be in your target audience and do some cheap, down and dirty research to see where you're losing most of them, and WHY.