wrong forum but--
your best bet right now is skyscape.
sells their ipod touch products as yearly subscriptions.
first you download skyscape (free) from itunes. this program is the main shell program that will contain all your purchases. it comes with a few junky freebies.
you can then go to their website
and purchase the subscriptions for whatever products you want.
make sure you select ipod touch or iphone as your platform!
it is the second, cheaper price. for example, davis's drug guide for nurses has two prices listed,$49.95 and $37.96. click the dropdown box under 37.96 to select iphone/ipod touch 1 year subscription.
purchase your product but remember it is a yearly subscription.
then load your skyscape program on your device, and enter the serial numbers etc, it will then download the program to your device.
the good news is there is a lot to choose from, major drug books like mosby/davis for nurses, medical dictionaries, etc etc.
the bad news is its subscription. some books like drug books i like that model with, as i always want the current version. other books like medical dictionaries...not so much.
for a free drug product there is epocrates...a tip with epocrates is if your looking to see what a drug is for, look under dosing.