Abby was able to get the Disability Access Service Card, which made it possible for her to wait for a ride inside in the air conditioning rather than having to stand for a long time out in the heat. Basically, we walked up to the Fast Pass attendant and he/she wrote down on our card when we could return for the ride. When that time came, we went through the fast pass line. While we were waiting, we could ride another ride with a short wait time, get cool, eat, or take a bathroom break. (You could only use the DASC for one ride at a time.) It was extremely helpful in protecting Abby from the heat. With her reduced lung capacity, she has to breathe much harder in the heat. We did our best to keep her cool, but waiting for a ride for 90 minutes just won't work for her.
If you or your child has a disability, I would highly recommend that you get the DASC when you go to Disney World. I know there's been some grumbling about the new card versus the way they used to do it, but I thought this worked out very well and was exactly what we needed. I also never used the old method, so I don't know any differently!
We also had a tag for the stroller that allowed us to take it in line (treating it like a wheelchair because Abby can't stand for too long), but it wasn't really necessary because we were able to go through the fast pass line. If we weren't able to use the DASC for a ride and it was a long wait, I would have used the stroller tag, but that didn't happen.
FYI, they have a similar program at Lego Land. It is not advertised at all and there's not a single mention of it on their website, but it is set up the same way as Disney World's program. We didn't use it much at all because the lines were much, much shorter, but it is nice to know that they have it if you need it.
It's very nice that they have these services at Disney World. Otherwise, Abby would have really struggled and we probably wouldn't have gotten to do nearly as much as we did! I think it's especially important in the summer when the lines are long and it is very hot. I am interested to see what Disney is like during other times of the year and whether we would need the pass as often. I would venture to say we would not.