I am a little fortunate though not working, the family business is using a different software and I can tinker a bit on it sometimes. That's what I was doing in my last job, tinkering anything on the system to discover something that maybe useful to the company.
I never get tired of playing around the software/system because there are lots of facets you'll know. One is the payroll software. It is very interesting but at the same time highly confidential so access to the test environment is only limited to authorized person. How I wish I was given the chance to mess with it.