Learning - Everyday there is something new to learn, understand and master.
Technology makes auditing interesting.
There is always more than one way to do the same thing and who is to say which is the correct or best way. Understand business processes then apply technology to that process. Technology is not the process only a vehicle to expedite a process. People skills - Everyone you encounter will be 'proud' of their work and you must not destroy their pride. Auditing is there to improve a process not identify who did something wrong.