I took the Flyer once before with my family and really enjoyed it. I thought that the ticket was a bit pricey but it was a family outing and it is the tallest observation wheel in the world, well, until the one in Beijing is completed, that is.
I was just surfing for promotions and good deals when I stumbled upon this. On 16,17, 23, 24, 30 and 31 October 2010, the Singapore Flyer will have special attractions which are free in nature: "Spooky Rainforest" and "Halloween Photo Stand-in".
Read about it here.