4 links
CiteSeer.ist
citeseer.ist.psu.edu
E-print database of mathematics and science papers with citation information. Papers may be added by specifying the URL where their files reside.
Directory of Open Access Journals
doaj.org
Covers many free full-text mathematics and scientific journals (most are peer reviewed).
Project Euclid
projecteuclid.org
Full text access to the journal Annals of Mathematics; a limited number of other journals available through paid subscriptions to Project Euclid.