I'm going to say this only once: don't judge a club by its name. Some clubs are real and active, despite them sounding weird (e.g. Circus Society and Medieval Society). Some are not (e.g. Chocolate Society). There are some clubs that literally do nothing other than take your $5 and hold one event all year, which is composed almost entirely of a close group of friends. Others just don't do much - I won't name any individual one, but if you ever talk to me or PM me I can list some and elaborate. There are some clubs that don't do much, then there are clubs that are run by some really passionate people and hold a lot of events/activities that you will get a lot out of.
The only real way to find out is to ask around. The Yellow Shirts (shameless plug) during O-Week tend to be really active and have been part of a lot of clubs, I recommend you ask them for their personal opinions of which clubs are good.
I haven't been a member of every club, but I recomend the following ones in no particular order (if they interest you):
1. <B>NUTS</B> - Theatre society. NUTS puts on a lot of shows during the year. If you want to be in the cast or tech crew then you need to join. Alternetavely you can join and get a $2 discount on all their shows. Some non-NUTS shows will also give you the $2 discount if you are a member.
2. <B>Studio Four</B> - Comedy society. They run free weekly improv workshops (think Whose Line is it Anyway), Theatresports competitions, comedy shows, etc. It's less than a year old but has a very active memberbase.
3. <B>UN Society</B> - Self explanatory. They generally run seminars. For example, last year they had a seminar you could attend where a former Australian diplomat who was the Australian ambassador to the UN security council was speaking. They've also had Edward de Bono and a former assistant to Kofi Annan. It's also responsible for putting together the UNSW group of the annual UN Model Conference.
Then there are the other clubs and societies:
1. Nationality-based (e.g. Indonesian Students Association)
2. Religion-based (e.g. Islamic Society)
3. Course-based (e.g. Law Society)
4. College-based (e.g. New College Students Association)
5. Politics-based (e.g. Labor Club)
6. Sports-based (e.g. Windsurfing Club)
I can't help you with these much, other than to say that you are usually an automatic member of your constituent society (e.g. I'm a member of the Commerce and Economics Society, being an Economics student, the same for Med Soc, Law Soc, Software Engineering Soc, etc).