Comment on Why Nofollow PR Sculpting is Bad for Search Engine Optimization by Mark.

Viral Marketing Dave, I have the same issue you have. I have been trying to promote subscribers. I recently added subscribe by mail. With the exception of a real niche site most people find my sites with organic searches, rather than subscribing.
I think to get people do subscribe it is an art in itself. My friend has 100s and a loyal fan base, but he uses give aways and contests etc. He puts a lot of effort into it. I do not have the time or focus for that.
The advantage is you are independent of search engines, and loyal fans often market you and generate a lot of content for you in comments.
How you achieve this is another story, maybe it is connected to the type of site or just marketing.
On the other hand nothing beats organic traffic from search engines to make your site grow fast.