I used uptodate a lot for the medical issues in my surgical patients (e.g., pt had surgery now has pneumonia). If your school subscribes to MD Consult, Sabiston is on there, which meant I used it a lot. If I was home or in the call room (yeah, right) I'd use Lawrence, but the necessity of having a physical text with me at the moment I had 10 minutes of downtime really killed it for me.
Anka