Hi,
Epocrates at
www.epocrates.com has a free version with some tools including drip calculator to enter the drug concentration, patient weight, and desired dose to get the drip rate. Not as many ICU type drugs listed in the Rx part, though.
www.skyscape.com has lots of books including many RN specific. They are basically electronic versions of paper books and cost about the same but are updateable. They also have a free medical calculator called Archimedes that does some nice stuff.
There are some nice PalmOS programs (on PalmGear) I used with my Sony that I am trying to run with the Styletap emulator but with limited success.
Hope that gets you a place to start looking.
Brian, ARNP