I got an iPad as a gift earlier this year. I use it in my home gym. Here's how it looks on my treadmill:
It was pretty simple to do this. I got some double sided velcro tape and put two strips on the treadmill:
And then I put two strips on the back of the iPad:
If you have more than one type of workout machine (ie treadmill and elliptical), you can move the iPad back and forth between both.