The Electronic Library of Mathematics : Mathematical Journals
Most are free, but some have a moving wall.
http://www.emis.ams.org/journals/index.html

ERIL: Electronic Resources in Libraries
List Issues -- Open Access (Journal) Collections
This list says that it was last updated in 2003.
http://www.joanconger.net/ERIL/list_issues_openaccess.html

Kimberly Montgomery
Electronic Resources Cataloger Librarian
Cataloging Department
University of Central Florida
kmontgom@mail.ucf.edu