I'm not yet an intern but I use my Treo and PPC regularly. ePocrates is probably the best one stop shop for multiple needs. Get a drug rep to sponsor your subscription, then you get the program for free. I also use several Skyscape programs: Griffith's, DrDrugs, Tabers, etc. I like all the programs I have because I seem to use them all.
I, too, would be interested in hearing about any patient tracking software.👍