Apple has added a new "Quick Reads" section to the iBookstore, promoting short, inexpensive titles. The collection includes everything from manuals to short stories, each selling for US$5 or less.
Amazon has featured short (typically 5,000 words or so), inexpensive titles as "Kindle Singles" for some time at approximately the same price point. It's unclear if Apple's Quick Reads are a direct response to Amazon's efforts, for if it's experimenting with brief, low-cost titles.
If you've got an iPad and an inclination towards a book you can finish in a sitting, you might find one to suit your fancy there.