I am all about the free shareware for the palms...
1. Epocrates--very useful. I use it in lieu of my pocket pharmacopeia. You also get the ID guide for the 1st 30 days when you sign up as well.
2. Eponyms--very useful as well. I use this daily on most rotations I've had thus far. For all those diseases/signs/symptoms named for someone that you've never heard of until pimped OR you just can't keep straight (i.e. is that a Kernig sign or a Brudzinski sign?). I've been pimped on a few eponyms not in there, but it's a very comprehensive list overall.
3. Diagnosaurus (dxsaurus)---available at diagnosaurus.com. Useful early in third year to give you a differential diagnosis (not much else) for symptoms and/or diseases. I don't use it much, especially now, but it's free and some people really like it.
4. Medcalc or MedMath or MedRules---useful and/or fun calculations (how many days old am I? What is his Creatinine clearance? etc.)
I don't know how to use AvantGo...it came with my palm but nothing happens when I go into it except for options of "server" "add" "delete" and so on....can anyone out there explain to me how to use this program?
4. Miscellaneous---things acquired from others who found them useful (probably found on the internet somewhere, but I got beamed from others). These include an Immunization schedule, PalmEKG, MentSTAT. Ask around...there's a lot of cool programs out there to be found.