I've found at least a dozen free dofollow search engines posted here and on other forums. I've found 90% of them to be complete junk and a waste of time. But I assume a couple of them must be decent. It seems that these are the most popular. http://www.inlineseo.com/dofollowdiver/ http://w3ec.com/dofollow/ http://www.commenthunt.com/ http://dofollow.radpixels.com/ http://atniz.com/dofollow-search-engine/ Let me know if there are others and please vote in the poll. I'm going to write a review comparing the best and most popular.
I will add two more to this list: http://directoryblogger.com/dofollow-blog-search/ and http://dofollow.radpixels.com/ RadPixels guys don't use google custom search unlike others. They add 'RSS' of the blog to their search engine. Oops, you already have Radpixels. I can add http://www.followtopia.com/ to your list