In order to get all needed knowledge books and papers are still an important part, beside surfing around the web. Even being on the road it is easier to read a book/paper.
I chose to buy a kindle and to use the kindle apps on my apple devices and on the pc and I have to admit that it is a very mature technology. Your markers and bookmarks get synchronized across all apps/devices and you can add your own books as PDF's or MOBI. Even on those "personal" files notes and highlights get synchronized!
I bought some books from amazon but I bought as well directly from O'Reilly and Packt Publishing as they provide MOBI and PDF at the same time and with some more services or even cheaper than on amazon. It works great to include them as "personal" files. There is even a kindle upload app for windows which integrates with the explorer and is very easy to use.
Great tool and service.