Answer:
USCIS Texas Service Center often issues the Request for Evidence in EB1 Extraordinary Ability petitions with respect to the criteria of "judging the work of others." TSC examiners question the alien applicant's work in acting as a reviewer for scientific journals, if the journals at issue were not the highest ranked journals in the field. Under the law, serving as a referee for scholarly, peer reviewed journals meets the "judging the work of others" criteria, even if the journal is not the highest ranked journal.
Previously, USCIS officials acknowledged that serving as a reviewer for a recognized journal is an acceptable form of evidence in an Extraordinary Ability case. They also confirmed that publication of articles in any ranked scientific or academic journal would fit within the types of publications required as proof in EB1 and O-1 cases.
It is not necessary that the journal must be the highest ranked in the field. Of course, the ranking of journals will be weighed with all other supporting evidence in determining whether to approve the EB1 case, and we all know the importance of the peer review process. To answer the RFE, you should get letters from editors of journals that you have reviewed articles.
http://www.greencardapply.com/question/question09/question09_0201.htm