I am starting a list of scanned type specimens online. You are free to add more links. 
For resource that deal with lettering/sign painting, please use this topic. 

 

Flickr Type Specimen Group
https://www.flickr.com/groups/type_specimen/pool/

William Caslon – A specimen of printing types (1785)
http://www.archive.org/stream/specimenofprinti00caslrich

Caslon: A specimen of cast ornaments (1798)
http://www.archive.org/stream/specimenofprinti00casl

Franklin type foundry, Cincinnati – Convenient book of specimens (1889)
http://www.archive.org/stream/convenientbookof00allirich

Barnhart bros. & Spindler, Chicago – Book of type specimens (1881)
http://www.archive.org/stream/bookoftypespecim00barnrich

Keystone Type Foundry, Philadelphia – Abridged specimen book (1906)
http://www.archive.org/stream/abridgedspecimen00keysrich

Cleveland Type Foundry – Catalogue and book of specimens of type faces (1895)
http://www.archive.org/stream/cataloguebookofs00clevrich

Palmer & Rey, San Francisco – New specimen book (1884)
http://www.archive.org/stream/newspecimenbook00palmrich

American Type Founders Company – American specimen book of type styles (1912)
http://www.archive.org/stream/americanspecimen00amerrich

Lanston Monotype Machine Company – The monotype specimen book of type faces (1922)
http://www.archive.org/stream/monotypespecimen00lansrich

Inland Type Foundry, St. Louis – Specimen book and catalog (1897)
http://www.archive.org/stream/specimenbookcata00inlauoft

MacKellar, Smiths & Jordan Co, Philadelphia – Specimens of printing types (1892)
http://www.archive.org/stream/specimensofprint00mackrich

Selections from the specimen book of the Fann Street Foundry (1874)
http://www.archive.org/stream/selectionsfromsp00fann

Fifteenth book of specimens from the Cincinnati Type Foundry (1882)
http://www.archive.org/stream/fifteenthbookofs00cincrich

Condensed Specimen Book from the Boston Type Foundry (1860)
http://www.archive.org/stream/condensedspecime00bost

Specimen of printing types from the foundery of Binney & Ronaldson, Philadelphia (1812)
http://www.archive.org/stream/specimenofprinti00binnrich

Book of type specimens by Barnhart bros. & Spindler in Chicago (1907)
http://www.archive.org/stream/bookoftypespecim00barnrich

 

Edited April 12, 201511 yr by Ralf Herrmann

The Silver Buckle Press Collection

• Add "punch" to your printing with Hamilton wood type (1951)
• Woodtype: selective emphasis for fine typography (1960)
• American line type book: borders and ornaments price list, printing machinery and material (1906)
• Bauer Types in Use
• Thibaudeau, F / La lettre d'imprimerie: origine, développement, classification and 12 notices illustrées sur les arts du livre (1921)
• Two-series modernage typography introduced by the American Type Founders Company
• The Nubian: a new fashion in types
• Hamilton Manufacturing Co. (Two Rivers, Wis.), Wood type, Hamilton Manufacturing Co., 1938

 

 

Morgan Press / Wood 2 (1964)

Wm H. Page & Co. / Specimens of chromatic wood types, borders, etc

What I would most welcome would be online copies of European metal foundries, especially after 1900. There isn't much available that I have been able to find.

Edited March 22, 201511 yr by George Thomas

Here is the only fully scanned German one I could think of:

Bauerschen Gießerei, Hauptprobe in gedrängter Form, Frankfurt am Main
https://archive.org/stream/hauptprobeingedr00baue

 

We are happy to announce the release of the first complete electronic issue of the seminal 1923 edition of the American Type Founders (atf) Specimen Book. Considered by many to be the culmination of specimen printing, it is an important, and massive, volume which has been unavailable until now.

http://sevanti-letterpress.com/download/1923-atf-specimen-book-download/

Hamilton Manufacturing Co. / Wood Type #38 by Hamilton

Just cover shots, but Henning Krause’s collection is still a joy to look at:
https://www.flickr.com/photos/59825996@N00/sets/72157601971266865/

Manuale Typografico, 1818
http://www.rarebookroom.org/Control/bodtip/index.html

 

1789: Anzeige der Lettern u. Schriften, sammt derer Benennung, wie auch einiger Leisten, und Vignetten. Augsburg

Daily Type Specimen. A tumblr page by James Puckett. http://dailytypespecimen.com

 

Type specimen scans by Kris Sowersby: https://www.flickr.com/photos/20994543@N04/sets/

 

At the end of the 18th century, the German printer J.F. Unger tried to create a new typeface that would bridge the traditional German blackletter designs with the Roman typefaces which briefly became more popular at that time in Germany. This is a specimen book (named “Probe einer neuen Art Deutscher Lettern”, 1793) he published to show and discuss this new design.  

Barnhart Brothers & Spindler / Pony specimen book and price list (1893)

BODONI LIBRARY—Website designed to encourage awareness of the products of the printer Giambattista Bodoni

http://bibliotecabodoni.net/en/library
 

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I don’t know who is behind it, but Flickr user “Typefaces World” has also a nice collection:

https://www.flickr.com/photos/typefacesworld/

 

While the Letter Library site will take some time to get public, there is already a constant stream of interesting images posted on the accompanying social media channels. The type specimen collector @robertmichael has just taken over the Instagram account and the content from there is now also published to our channels on Tumblr, Facebook and Twitter. Feel free to follow us there, if you use any of these network sites. 

Some french specimens at 'Musée de l'imprimerie et de la communication graphique'
http://collections.bm-lyon.fr/mil/search

Proben aus der Schriftgießerei von Karl Tauchnitz in Leipzig
http://daten.digitale-sammlungen.de/~db/bsb00001210/images/index.html?seite=3&pdfseitex=

 

A few scanned type specimen books:

http://archiviotipografico.it/en-GB/collection/books

 

B.G. Teubner, Leipzig, 1846. Full Scan:

http://digital.slub-dresden.de/werkansicht/dlf/14560/1/

Since 2005 I have been listing specimens of characters that are available on the web. I have around 250 of them today. They are listed here: http://jacques-andre.fr/faqtypo/BiViTy/index.html

I have included as well technical manuals and others matters connected to type making.