Can someone help me with a networking problem?

I’m volunteering with a public health NGO in New Delhi that serves the very poor. With two mobile clinics, seven part-time doctors and about 10,000 patients a month the environment is pretty fast-paced. Each patient is seen for only a few minutes, for free, and receives free medicine.

The NGO wants to start keeping track of patients using an electronic database. Ideally, the doctors would take the patient’s details and prescriptions using a hand held device (something like an iphone) that’s networked into a central server.

A company that designs electronic health record systems for doctors and hospitals in the United States has offered to provide their services for free, but their applications are all web-based and because of the quick turnover at the clinics and very slow internet speeds on wireless devices here in India that’s not ideal.

The clinics visit slums in and around New Delhi in three hour intervals. What I’d like to do is allow the doctors to take their patient’s information and prescriptions and send them using a wifi network, quickly, to an off-line server that would, at the end of each shift, deliver the information to an online server.

Does that make sense?

If so, does anyone have any advice on how to network handheld devices together off-line? Any advice on what platforms to use?