hannamyluv - 3:30 pm on May 11, 2004 (gmt 0)

I'd look first into how to get more people to your in-house. Are you asking for an email address at EVERY touchpoint? Is there an email sign-up box on every page? Have you tried to run a contest or give away something for signing up (like a coupon)?

These are better ways to take advantage of your visitors to your site.

As far as getting new visitors, I would suggest testing PPC, if you aren't doing it already. Your ROI would probably be better.