Yes, I have several, but can't say that I use them much. When you go to the App Store put Quilting in the search box. Hopefully, others can let us know of quilting apps they actually use. What I DO use my Ipad for is downloading PDF files with project instructions to take to my sewing machine (I don't have WIFi in the house so my PC is nowhere near my machine) You need a PDF reader for this, I have GoodReader.
The other thing is for sketching blocks and/or doodeling (sp?) quilting patterns. For this, I like Penultimate. I also use Calc&Draw, which is a sketch pad with a built in calculator (duh)I can sketch something and then calculate the number of blocks or yardage. I know that there are dedicated quilting apps that will do the calcs, but for me this is much easier. On both the draw programs, if I come up with something I want to keep, I can save it for future reference. I have the original with no camera, but I would really use that to capture ideas!