Start with the Wikipedia entry for the Apostle John.
The About.com Christianity page offers information about John.
The article on John in Encyclopedia Britannica is found here.
You find several bible verses that tell John’s story in this post.
Here is an excellent article on John the Apostle.
There is more than one John, so be sure you’re reading about John, the disciple or apostle, not John the Baptist in this post.
The Orthodox Church offers this entry on John.
Scroll down to John in this listing of the disciples.
a student project on John the Apostle
The book of Revelation is credited to John. Here is an article with one way of looking at this enigmatic book.