Discrete Analysis – A new type of math journal
gowers.wordpress.com
gowers.wordpress.com
Also interesting to see that they haven't decided to change much about the peer review process. The arXiv overlay structure prohibits a practise that I've been hoping to see introduced, which is blinding reviewers to the name/s and institution/s of the author/s.
As an author, I can usually identify the anonymous reviewers as well, if they are not outsiders.