I've mentioned before about using kindlegen & formatting in HTML for kindle publishing (e.g.: How to make a kindle ebook full of images). Recently I had to create internal links within my eBooks. A map is unlike a traditional novel, since it's not a one-page-after-another reading method, more a jump around to another page method. This is how you mark up internal links for Amazon Kindle eBooks to allow internal navigation and internal links:

For each point that you want to be a link, choose a short name for it with no spaces (like mainsection), then put this snippet of HTML in:

<a name="mainsection"></a>

Don't put anything inside the tag, and you must put the name as the name attribute, and don't use any href.

If you want some text to link to this part of your book, just put this in:

<a href="#mainsection">Some text here</a>

Then the text Some text here will be an interal link that, when clicked by the user, will take them to the mainsection part. You must put a # in front of your section name.