A little searching on Google will uncover dozens of web sites devoted to handheld computers and those using the Palm OS in general. The devices to look for are the Palm family, the TRGPro and the Handspring Visor; they all use the same Palm operating system and so will run any software designed for it.
   I've found the following sites to be particularly useful.

Jim Thompson's Palm Pages  
Dr. Thompson is an emerg physician in Charlottetown. His site has solid reviews on Palm applications, written from the point of view of the busy practicing physician. There are also links to other good sites. This is a good place to start if you want to get a sense of what a physician would use a handheld computer for.

Handheld Med   
This was a better site before they junked it up with a lot of commercial offerings. Anyway, if you look closely at the menus along the side and top, you'll see links to software reviews, editorials and press releases about handheld devices in medical school and clinical practice. Worth a look.

PDAMD.com  
Another site at risk of drowning in ads but I suppose that's how they are able to keep the site running. Good reviews on software for medical applications. Some case studies of how physicians and hospitals are using handhelds and links to very relevant software.

MD Helper  
A good collection of medical links and a few software programs for clinical practice. Jay Mercer (McMaster Class of '93) is one authors of this site. Look for him also on LearnLink in the Handheld Users' Group folder.