This would make for a great link on your iPads or iPods if you are using them as learning centers in a classroom. And with an audio splitter, you can have two students sharing one iDevice.
Another online resource for beginning readers that can be used on an iPad or iPod is called Tar Heel Reader. Books are designed with one sentence per page accompanied by some image. You can filter your search by topics to find books of a particular interest. Below is an example choices from the category "Books from Alphabet".
This website offers a collection of a few thousand books with options to have books read to the student, where you choose the voice. Since the books at Tar Heel Reader are written for all beginning readers, most of the content is perfect for younger readers, though some of the books might be more appropriate for older students. Find the most appropriate category for your students and save a direct link to those books on your iPad or iPod.