Might I add the following books by James Gunn to the list for anyone interested in the history of science fiction. These books are all outstanding.
http://www.amazon.com/gp/product/081...SIN=0810844141
This site is also quite good as well. Don't recall exactly how I ran across it but I think it is really good.
http://www.sf-foundation.org/
And I would also suggest this site for people looking to get into reading and learning about science fiction. Something for almost everyone can be found here.
http://www.magicdragon.com/UltimateSF/SF-Index.html
Enjoy if you will.