Timothy Seid's site gives a brief introduction to textual criticism with an example comparing three versions of an English text written in all capitals without spaces between the words.
The primary aims of the Early Greek Bible Manuscripts Project are to build up the holdings of facsimiles, photographs and microfilms of biblical manuscripts in the Tyndale House Library and to encourage research in this area.
While little of the University of Michigan’s Papyrus Collection is currently visible online, the web site does provide an interesting basic introduction to papyrology.
Wallace, Executive Director) has ambitious goals that include making digital photographs of Greek New Testament manuscripts, creating exhaustive collations, analyzing individual scribal habits, publishing, developing electronic tools for analyzing New Testament manuscripts, and cooperation with other institutions sharing similar goals.
The Centere has already made available images of a good number of manuscripts.
There are more than 600 Greek manuscripts ranging in date from the 9th century to the 18th century included in the British Library's Digitised Manuscripts site.
The library holds approximately 1,000 Greek manuscripts, and intends to digitise the remainder in the next three years.
In addition to what is avalable in the printed edition, transcriptions of important manuscripts are provided by the Institute for New Testament Textual Research at the University of Münster, Westphalia, Germany.
You can search the Duke Papyrus Archive, a repository of papyrii covering a wide range of topics and time periods at the Duke Libraries website.
The institute describes its mission as “to research the textual history of the New Testament and to reconstruct its Greek initial text on the basis of the entire manuscript tradition, the early translations and patristic citations.” See the comments above under "Digital Nestle-Aland Prototype." David Robert Palmer Has provided a useful listing of New Testament manuscipts much like the one found at the back of the UBS Greek New Testament, but with a number of added features, including links to images of the manuscripts.
provides a Papyrological Navigator that aggregates and displays information from the Advanced Papyrological Information System (APIS), the Duke Databank of Documentary Papyri (DDb DP), the Heidelberger Gesamtverzeichnis der griechischen Papyrusurkunden Ägyptens (HGV), and Bibliographie Papyrologique (BP).
It also provides links to Trismegistos (See further below).