General Working Papers:

Arxiv 
Vixra  
SSRN (Huge collection)
Ideas 
Econoacademics

EconPapers: Very large collection of economics working papers
Look at Repec too

University wise working paper series:
Harvard Working Paper 1
Harvard Business School Working Paper Archive 
London Business School Working Papers
Sloan School of Management Working Papers Index
University of Chicago Center for Research in Security Prices (CRSP)
University of Michigan Business School
Yale School of Management

International Organizations: 

Federal Reserve Board: Working Papers
Federal Trade Commission
International Monetary Fund Working Paper
OECD Economics Working Papers

NBER Archive

Quality of journals:
http://www.bizschooljournals.com/node/4
http://www.associationofbusinessschools.org/sites/default/files/abs_lightningwintro.pdf
http://www.scimagojr.com/journalrank.php