A first and very nice version of the Tractatus made by Jonathan Laventhol back in 1996! As the author says: "You will have to make up your own mind about whether such a tool helps or hinders your appreciation of the book. The curious who wish to dip into Wittgenstein will like the web pages; anyone actually wanting to read the whole book is is recommended to read the paper copy in a silent room with pencil and paper handy."
Another project which aims at modelling the domain of philosophy, so to create a dynamic reference system for the Stanford Encyclopedia of Philosophy
A free and experts-peer-reviewed encyclopedia of philosophy on the web. The Encyclopedia was created in 1995 by Edward N. Zalta, with the explicit aim of providing a dynamic encyclopedia which is updated regularly, and so does not become dated in the manner of print encyclopedias. The charter for the encyclopedia allows for rival articles on a single topic to reflect reasoned disagreements amongst scholars.
A hypertextual and collaborative approach to the works of Nietzsche - for sure one of the first attempts of this type in philosophy!
A recent EU funded project for investigating how philosophers' lives could change in the era of digital publishing. From the site: 'Discovery will contain an extensive, semantically structured digital library of reliable scholarly editions of philosophical texts, high quality reproductions of primary sources, peer reviewed essays and a rich archive of videos including lectures and interviews featuring leading contemporary philosophers. This multilingual collection will be freely available and will be constantly augmented by user contributions'.