I involved in building 2 systems for healthcare:

Patient privacy monitoring (ensure no one peeks into patient records inappropriately) and medication analytics platform (monitors suspicious and anomalous activity related to drugs and opioids diversion).

This of course deals with multitude of different systems, EMR's, data formats, legacy-everything etc, but the GREAT about this whole thing - is opportunity.

No one really tackled a challenge of visibility across different systems and data formats in Healthcare and it's lots of fun to be part of that.

("Fun" is non-corporate word - but it still fun!)