During my medicine rotations I had a sheet of paper with me at all times keeping a mini soap note as drizz had suggested. During my surgery and ICU rotations we kept an excel worksheet on all the patients. We updated them in the afternoon before leaving with any new abx, procedures, radiology results, etc...this way we could print it out for when we signed out. Also, if you were on call you were expected to do the same before leaving and thus we had an updated sheet. Usually at night there should be too much changed since the attending was doing rounds at night.
During rounds I printed out my SOAP note on the patients which had all of the new stuff. Add the mini soap note from previous telling me the original story and the new SOAP note of day and overnight stuff and I got most of it covered.