In terms of part-time work, tutoring is excellent, especially working for yourself. A private tutor can pull anywhere from $30-$70 an hour cash and you aren't really going to make money like that elsewhere. I ran my own small tutoring business for just over four years and I managed to earn more than enough to keep myself comfortable as a uni student. I did however cut back in my last year of uni to make more time for a job related to my degree and future career, but looking back, this was a mistake as I would have been able to handle it.
However, the main drawback of tutoring is the lack of regular guaranteed employment. That being said, the demand is definitely out there and the key to making it work is offering a high quality service, because word-of-mouth is essential to getting work. As a small business owner once told me "When you run your own business, you have to be competitive every day of the week". Working as a tutor isn't like working at Coles where you can get away with a half-assed effort, if you don't offer a quality service you wont get more work. It's that simple.
Speaking of Coles, another good job is stacking shelves at a supermarket. My mates work at Coles doing night shift (8pm-12pm) and they make $20.2 an hour, plus time and a half on Saturdays and double time on Sundays. From what my mates tell me, the work is pretty easy and for the money, it definitely seems like a sweet number.