Some examples
Presenting the Half Title page and/or the Title Page as an image, rather than as plain text, can add greatly to the visual appeal of an ebook, and these pages are among the first that the reader will see. Images take time to load, so it is important that the image be sized properly and optimized in order to load quickly. Also, the Kindle will resize photos it thinks are the "wrong" size. Proper sizing keeps that from happening.
Here is a sample of a Half Title page displayed as an image on the first generation Kindle:

By using an image we were able to preserve the font (ebook devices use their own standard fonts), the layout, and the half-tone Roman numeral I.
The Kindle has its own menu to enable the reader to navigate to different parts of an ebook. An ebook should always have a linked Table of Contents, and the Table of Contents and Go to Beginning items should always be enabled on the Kindle menu.

If this menu is not specifically created as part of the ebook, the Table of Contents and Go to Beginning menu items will appear grayed out on the Kindle. Even though the ebook may have a linked Table of Contents, if it does not appear in the Kindle menu, the reader will have a difficult time navigating to it. The Go to Beginning item usually links to the first chapter of the book.
You will note that the Go to Cover item displayed above is grayed out because the ebook is currently displaying the cover.
