A service offered by the good people of Oreilly Books
This web site offers up the texts of many of their techinical books in web page form, easily browsable. You pay a fee (the cheapest plan is $9.95 a month), and get access to a number of books based on the fee (5 for the cheapest.) You can switch these books out every month, or keep the ones you want to have access to. They also offer site-based subscriptions for businesses and organizations.
I think this concept is not only very nice of the Oreilly people, but also very practical. For even a small company, keeping the technical staff in books can cost hundreds of dollars. Whereas with this service, you can pay a small, flat fee, and have access to as many books as you need, all online. I hope this business model picks up in other areas.