I’d been meaning to do this for a while, but I finally got a balance ball and have been using it instead of a desk chair when I work from home (which is about 50% of the time). I got a regular Reebok version at Target for something like $21. It looks like this:
I got the 75mm one so that it is tall enough to pull up to the desk.

You can get fancy schmancy chair versions of the balance ball made into a chair for ridiculous amounts of money ($80? $100?).

But what kind of fun is it, if you aren’t constantly faced with the possibility of falling off and breaking your tailbone?!

The first day I had the ball as a chair, I got carried away and bounced on it a little too much. I almost fell off a few times. I also allowed the cat to sit in my lap, on the balance ball. I was very careful of her claws. She didn’t seem to mind it.

I have been more conservative in my bouncing the last few days, and have found that I should probably limit the time on the ball to around 3 hours at a time, since it doesn’t create the most ergonomic position for typing. Also, after sitting on it for 8 hours the first day, my abs HURT at the end of the day!

Just think how OMG ripped I am going to be! If I don’t break my neck first.