Open Access links

Preprint databases (repositories)

• arXiv (Open-access to >400.000 e-prints mostly within the exact sciences)
• HAL (french research repository with over 40.000 eprints)
• e-print archives using the EPrints software (mostly university IRs, e.g. the German electronical library  elib)

Danish subject portals

• Historieportalen
• Det Virtuelle Musikbibliotek

Journal databases 

• DOAJ  (Directory of Open Access Journals, more than 2500 journals)
• Open J-Gate (approximately 4000 journals)

Danish research databases (usually not full text repositories)

• CURIS (Copenhagen University): Not yet open (PU:RE system), replacing PUF
• KVL's research dtabase (KVL, KU): Full text for some papers and the possibility for researcher submission (PU:RE system)
• The Danish Research Database (DEFF): Sometimes external links til papers 
• VidenBasen (Aalborg University): Full text to some papers (PU:RE-system)
• RUC's research database (RUC): Does not appear to have full text (PU:RE-system)
• Orbit (DTU): Occasionally external links 
• CBS's research database (HHK)

Repositories

• ROAR (Registry of Open Access Repositories)
• OpenDOAR (Directory of Open Access Repositories)

Tools and software

• Eprints: Software for e-print archives (open source)
• Fedora: Software for databases (not to be confused with the Linux distribution or LDAP)