A custom built mobile business application we created recently made huge improvements in efficiency.
Data was being collected on paper in an environment that isn't suitable for laptops. On return to the office it was typed into a spreadsheet, then imported into a database.
We created a custom built application for a PDA to allow data capture on site and synchronisation to a SQL Server database on return to the office. We also created a Microsoft Access front end to the database for use in the office to report against the data captured on the PDA's.
No paper or duplicate data entry.