Laridian Electronic Publishing, makers of MyBible software is selling a tool called BookBuilder to create MyBible documents with native compatibility. Specifically, you get to create your own HTML tags and then convert the document into the native format allowing fast search, bookmarks, and addition of your own notes.
It is offered for both Palm and PocketPC, but it's hard to tell if they are separate products. They look the same to me in the pictures.
Product pages are:
PocketPC BookBuilder and
PalmOS BookBuilder.
(via Palm Addict)