The most useful 21 links

1. Digitized manuscript catalogs (Brigitte Pfeil)

http://www.ub.uni-kassel.de/handschriftenkatalogeonline.html
http://www.uni-kassel.de/ub/historisches-erbe/sondersammlungen/handschriftenkataloge.html

Please mail Ms. Pfeil additions: pfeil at bibliothek.uni-kassel.de

2. Online catalogues of medieval manuscripts (Albrecht Diem)

http://www.earlymedievalmonasticism.org/Catalogues-of-Latin-Manuscripts.html

3. Handschriftencensus manuscript catalogs

http://www.handschriftencensus.de/forschungsliteratur/kataloge

4. Medieval Manuscript Catalogs & Inventories (Robert D. Peckham)

http://www.utm.edu/staff/bobp/vlibrary/mscatalogs.shtml

5. Kristeller Online: Latin manuscript books before 1600

http://www.mgh-bibliothek.de/kristeller/

Please note that there is a printed addendum published in 2006.

6. Peraldus.ch: A collection of bibliographical references to medieval
manuscripts

http://www.peraldus.ch/

7. Looking for a manuscript in the publication Scriptorium and in the Bulletin codicologique

http://www.scriptorium.be/search_manuscript.php?lang=en

8. Hill Museum & Manuscript Library

http://www.hmml.org/research2010/research10.htm

9. Schoenberg Database of Manuscripts

http://dla.library.upenn.edu/dla/schoenberg/

AUSTRIA

10. manuscripta.at - Mittelalterliche Handschriften in
österreichischen Bibliotheken

http://manuscripta.at

BELGIUM/ THE NETHERLANDS

11. Bibliotheca Neerlandica Manuscripta

http://www.library.leiden.edu/special-collections/manuscripts/subcollections-whs-bnm.html

12. Medieval manuscripts in Dutch collections

http://www.mmdc.nl/

13. Online guide to mediaeval manuscripts in Wallonia - Brussels

http://www.cicweb.be/en/recherche.php

EAST EUROPE

14. Manuscriptorium

http://www.manuscriptorium.com/

Mostly Czech Republic

FRANCE

15. Bibliothèque virtuelle des manuscrits médiévaux

http://bvmm.irht.cnrs.fr/

16. Enluminures, Liber Floridus, Mandragore

http://www.manuscritsenlumines.fr/

17. Initiale - Catalogue de manuscrits enluminés

http://initiale.irht.cnrs.fr/

GERMANY

18. Manuscripta Mediaevalia

http://www.manuscripta-mediaevalia.de/

Please note: There are (i) descriptions and digitized catalogs in the
database, (ii) an old presentation of older digitized catalogs where
you can link directly to pages at

http://www.manuscripta-mediaevalia.de/hs/kataloge-online.htm

(iii) PDF-descriptions in the section "Projekte" which cannot be
searched (respective incompletely via Google site:search)

ITALY

19. MANUS - Censimento dei manoscritti delle biblioteche italiane

http://manus.iccu.sbn.it/

SWITZERLAND

20. Verbundkatalog HAN

http://www.ub.unibas.ch/?id=1469

Mostly modern materials but also medieval mss. from Basel, Luzern, St. Gallen (Vadiana), and Solothurn (to mention only the most important libraries with medieval manuscripts)

USA

21. Digital Scriptorium

http://bancroft.berkeley.edu/digitalscriptorium/

UPDATES

May, 2014

I should have mentioned

FRANCE

Calames
http://www.calames.abes.fr

July, 2014

Bibliografia dei manoscritti citati in rivista
http://tlion.sns.it/mssb/

December, 2014

MIRABILE
http://www.mirabileweb.it/

USA

Directory of Collections in the United States and Canada with Pre-1600 Manuscript Holdings
http://bibsocamer.org/wp-content/uploads/Conway_Davis_2014.pdf