I was amazed at this online tool. It lets you create 3-D boxes via Flash programming. It asks you to upload a cover, a side design and a top design. Using 3-D boxes to sell software makes the software look more professional (of course, whether the software is good or not is a different matter).
Tip: If you'd like to make a book, you can simply create a graphic that looks like pages of a book and you can upload this as the top of the box.