I also wanted to bring your attention to several articles and links about vertical birth.
First, read The Unnecesarean's fabulous article about the Vertical Birth Movement in Latin America. From Venezuela to Peru, from Ecuador to Mexico, hospitals and childbirth advocates are starting to adopt vertical birth as a way to increase safety and as a fundamental human rights issue.
Next, Susana of Spirit-Led Birth that birthing in an upright position liberated her from pain:
Once I learned that women can birth while sitting, standing, or on all fours I was liberated! From the bed and from pain! My first two births, (which were hospital births) were conducted in a bed. For the rest of my 5 births I never once laid in a bed. During my first homebirth I went to lie in bed, out of habit I guess, and as soon as I laid down I felt pain so I got out the bed and never got back in!She includes a link to a Spanish-language video called "Humanized Birth: Retrieving the Vertical Position." Lots of lovely upright births!
Finally, Sage Beginnings has photo illustrations of various birthing positions. These pictures, taken in a variety of birth locations, are so much more helpful than the line drawings found in many birth books!