Yoga ball-birthing ball--what can I do with it now?

About a year ago, I bought a "yoga ball" to use for situps, etc. I
was taking an aerobics class at the time where we used them for toning
every week. I had bought a workout video that had a section on using
the toning ball, and was doing it maybe 1 a week until around the time
I got pg (exercising more than 1x a week--I had a couple of yoga and
pilates tapes, plus cardio stuff at the gym).

Now that I seem to have enough energy to get off the couch again, I"m
trying to step up my exercise routine a bit. I have been doing cardio
at the gym 1-2 times a week (elliptical/cross trainers mostly) and/or
walking when I haven't felt too ill or too sleepy to move up until
now. I just recently bought a prenatal yoga video that should be
arriving from Amazon.com today or tomorrow.

Ok, now that I've given you the long version, here's my question: I
still have my toning/yoga ball. Are there any good
books/videos/websites that describe good exercises I can do with it
during the rest of my pregnancy? Most of the exercises on my original
tape don't really work (situps make my stomach muscles cramp up really
bad, and some of the other stuff involves laying on the ball face
down, which is really uncomfortable). I think the ball that I have is
similar to what everyone calls a "birthing ball" but I've never seen
anything that describes what you actually *do* with a birthing ball
during (or before) birth (we haven't taken a childbirth class yet
either, so maybe that's where most people learn about them...?)

Thanks!
--Elit.
#1 due 9/20/2004