firstly to create a lookup form to allow staff to search for customers address details and attach them to the ticket easily. maybe the same way that the email lookup works.
then create a wizard type page that is mobile optimized (for ipad, iphone and android) where engineers are able to reply to a ticket with what they have done while they are at the customers office, have the customer sign the mobile using something like SuperSignature http://www.supersignature.com(http://www.supersignature.com) then have a report emailed to the customer and saved to the ticket as a PDF or something.
I think this would be very useful for alot of people however maybe a little more complicated than most mods