On the following site you will find 110 (for now) e-books in philosophy. They are (due to copyright issues, of course) mostly more than 50 years old and put together from varying sources. Some are pdf’s from scans of the book itself, others are in html or e-pub and there are even versions for kindles and i-pads. Quality varies greatly. Some are links to project-gutenberg files which are of good quality, some pretty wild scans, others University e-books of excellent quality. For now you have many classics such as Hume’s Treatise, Kant’s Critique of pure reason, also Aristotle, Plato, Wittgenstein, Russell, Heidegger, Arendt and so on.
Here is the link