OK, I made an offhand comment that I would post this info on my blog, and Christy held me to it (see her comment in the side bar) so here it is:
In many ways, you can think of the Book of Revelation as given to us in a series of 7's, some are explicit while others are simply implied:
7 churches (chaps. 2-3);
7 seals (chaps. 6-7);
7 trumpets (chaps. 8-11);
7 thunders (chap. 10);
7 signs (chaps. 12-15);
7 bowls (chaps. 16-18);
7 last things (chaps. 19-22).
Others like to divide up Revelation around four key visions:
(1) the vision of the Son of man among the seven churches (chaps. 1-3);
(2) the vision of the seven-sealed scroll, the seven trumpets, the seven signs, and the seven bowls (4:1-19:10);
(3) the vision of the return of Christ and the consummation of this age (19:11-20:15); and
(4) the vision of the new heaven and new earth (chaps. 21-22).