Alternatively, Books are a Pain.
There are a lot of oracle manuals (the 10gR2 database set alone has 225 pdf files), and the only practical way to read them is on a computer. Oracle will sell you hard copy manuals but they are £40 each which makes £9000 for the set. Plus the extension you will have to build to store them - at an average of an inch thick they will occupy almost 20 feet of shelving. Given all that, its no longer practical to keep up by reading a manual on the train to work or when you get a few minutes break.
If you have a Palm pilot or other PDA you can try reading the pdfs on that, but frankly the pdf viewer for Palm is rubbish and gives you about one line per screen.
Plucker is a brilliant alternative. It is designed to download websites and convert them to a Palm readable document, but you can use it to convert the html versions of the documentation. I haven't worked out the best way to deal with diagrams yet (who needs pictures anyway, we are not sql server types), but it is the most readable thing I have found in ages.