Does anybody get referrals through the non-credit based ones? Yes. But...it depends a lot more on the subject lines for your emails. Because what seems to happen is people filter those to separate folders and then skim through the titles to see if there are any they want to read. So your subject lines/titles are extremely important. I've sent the exact same ad with varying titles and got a huge difference in responses.
There are so many of these that it would be impossible for me to list them all, but I will list some to get you started. I will add more as time goes on :) Safelists you can sign-up for free, and then upgrade if you decide you like it, want banner impressions, more frequent mailing schedule, etc...
