Yes, I have had pretty good success with myblogguest.com. The best chances are those with the most recent postings in "looking for writers". I have about a 1 in 4 success rate in publishing when I feel I have strong content. Then look at all the blogs in the system database, they have a much lower response rate much less approval rate but I have find some gems.
I would imagine anyone publishing on over 300 sites would know this, but I have found some good contacts in the Cathy Stucker email, sign up at http://www.bloggerlinkup.com/. As a caution, I found when you offer the post and someone inquires about it, they have stolen it without linking. Check their site before you give out your content. If a site has posted needing content, always has been safe.
