Actually, I do happen to have some stuff to throw in to hopefully help out in some of the reasoning here . . .
Why is it the last book of the Bible?
First, it's not because of the "idea" that it's pertaining to the end of the world. But instead, it's because of the "way" it's written in that it's considered an "Apocolyptic" book.
Believe it or not, there were questions concerning all the books from Hebrews on through Revelation as to whether they should be added into the canon of Scriture. "That's" why the books are organized the way they are. There was specific criteria used to deciding whether or not a book would be considered part of the canon. One was, that the author of the book was obvious and verified. That put Hebrews in question because the author is uncertain. Some felt it was Paul who wrote it, others felt it was . . .nuts . . .can't remember the names . .but there were a couple other church leaders of that day who were also known to write a letter or two and because the way Hebrews seems to flow differently from the Epistles that Paul "did" write, many felt that either he had a ghost writer type of guy write it for him, or someone else all together, either way, Hebrews is located toward the end of the New Testament for that reason. Rather than remove it from the canon, they agreed, that because of the rich content, that it was authentic so they put it in the back.
Another criteria was the length of the letter, they had to be more than just a couple paragraphs . . .but . .. because again of the content in richness and it was clear who the authors were, the smaller books such as 1, 2, 3 John, Jude, 1, 2, Peter and James were toward the back as well.
But for Revelation, in that day, there were MANY apocolyptic books floating around between the churches. John's wasn't the only one. But John's "was" the only one that was authentic . . .many others were written by extremists who would sign as forgers of a disciple so that more people would believe them. It was actually the reason why the canon was put together in the first place. So that there'd be some continuity in the church over-all. It's why the Catholic Bible is different from ours in they've included a number of other books that the canon didn't.
there are actually a rather large number of canon Scriptures . . .I mean a large number of different bibles . . .not a large number of books, all though most of us are already aware of that. There are 66 books in "our" canon of Scripture . . .here a WIKIPEDIA link to the various ones put together over the years and a description of who did it and why.http://en.wikipedia.org/wiki/Biblical_canon#Canonical_texts