Handheld Learning - learning with mobile and ubiquitous technologies

Before we spend the time and effort, does anyone know if there an application available that operates on a smart phone or PDA (Windows OS - 5 or 6) that can be used as a counting tool.

For example, a student wants to count the vehicles and vehicle types (or anything else for that matter) that pass through a given intersection in a given time period. The data is recorded by simple screen taps, including the time of the recording. Any errors are quickly removed by a single tap. The student can work to an icon-based system (e.g., cars, trucks, bicycles, vans as simple graphics rather than text etc), but also has the ability to add another category if needed (e.g., tuk-tuks - we have a field trip to Thailand - I know its tough, but someone has to do it  )

In addition the tool displays a running total and maybe even provides a graph of the current data. At the very least, the information can be exported to as a cvs file to excel for further analysis.


Thanks
David