I had this issue a few months ago. Needed to to access custom applications on an iPAQ when not online. After many searches, questions and research I found that mNotes from Common Time was by far the best solution for our needs. Their support is superior to other competitors that I spoke with and the product is easy to learn and implement.
They assisted in custom mappings for our CRM solution to the standard PocketPC contact form. If you need further customization they also have a product called mForms.
http://www.commontime.com/
Hope this helps...