I like the free frontend and then try to convert them to buyers.

Last July Jeff Alderson and myself did a free butterfly site at www.webtoolsnow.com and we
promoted it 1 time.

So far we have over 20K members and every single day it still gets people
signing up.

They key is to make it easy to sign up and easy for someone to promote your site
after they join.

We have banners, emails, etc.

Talk soon
Charles