Tomorrow as part of the re-opening of the Cultural Centre at SouthBank, the Science Centre at the Brisbane Museum has free admission. It's normally $12 for adults, $10 for concession and $9 for kids so while it's not a huge saving it still counts as a bargain as far as I'm concerned!
I know it doesn't leave a lot of time for planning, but if you don't have other things to do it could be a good outing for the kids.
MOD EDIT - This looks like its expired on the 19th, but saxlady says they told her at entry it continues today. Check postings below for all details and decide yourself. BTW it appears while it's free, they do ask for a "donation" to the flood appeal, which is your choice
cool