(1) Directory of Open accces journals: (best to open in a new window)
http://www.doaj.org/doaj?func=subject&cpid=58

(2) EMIS Electronic Library of Mathematics (best to open in a new window)
http://www.emis.de/journals/index.html

(3) Publications de l'Institut Mathématique (Béograd)
http://publication.mi.sanu.ac.yu/pages/main.php

(4) Euler: your portal to mathematical publications (best to open in a new window)
http://www.emis.de/projects/EULER/

(5) HUB - Research papers (best to open in a new window)
http://www.hubrussel.be/eCache/HUB/15/115.html