An alternative to cutouts (usually called thumb indexes) is to have outside margins printed with your desired navigational aids. Consider the following two images, taken from subsequent chapters in a book:

An alternative to cutouts (usually called thumb indexes) is to have outside margins printed with your desired navigational aids. Consider the following two images, taken from subsequent chapters in a book:

Update

In reference to another answer posted to this question, if a multi-level solution is required, something like this should suffice:

A and its sub-indexes would start at the top of the page, B and its sub-indexes would start in the middle, and C and its sub-indexes could occupy the bottom third; D would start at the top, and the cycle would continue. When the book's pages are somewhat "fanned", you can easily see where to jump to.