A couple of very good online book sites have already been listed (general
interest: project gutenberg; computer books: informit), but I thought that
I'd add my two cents:
IT Knowledge offers newer books for $, but they also offer a pretty large
free archive of older titles. On the left side of their page, click on
<free archive>. The drawback to this is that you have to browse through
many pages to find what you want. Your other option is to click on
<advanced search> from the main page (it's right above the <free archive>
link, then use the pulldown menu to limit your search to books in the free
archive.
<http://www.itknowledge.com/>
I hope that this isn't too commercial...but I think it's safe to say that
all of the "best" computer books are published by O'Reilly. If you go to
their site, you can read parts of their books for free, including
forthcoming chapters, some introductions, and additional articles that they
post there. You may want to visit the specific <resource center> for your
topic. Again, free access is rather limited, but the information available
can be a good starting place. And if you're willing to pay, they have a
couple of collections of their books online (they call them "reference
libraries"; there's one on java and one on html) which can be accessed for
a little more than the cost of buying just one book. These may be worth
checking out.
<http://www.oreilly.com/>
Sorry if that came off as an O'Reilly plug; their books have just been
tremendously helpful to me. Along those lines, if there are any books you
own already that have been helpful, you may want to look for their
publisher's sites; many books even have their own site to which is posted
additional or updated information. Even if a booksite isn't mentioned in
the main text, check the first few pages. Sometimes you'll find something
buried in all of the cataloging and publishing data. If there's a book
that I'm considering buying, I always cruise around to see if I can't find
a booksite first; they often offer a valuable preview to help you make a
decision whether to buy the book (and sometimes you don't even need the
book anymore; the information is available on the booksite).
Warmest Regards,
Martin Lang
P.S. One more good general interest collection of online books:
The Bartleby Library
<http://www.bartleby.com/>
