VMware Fusion for US$34.95 (approximately $40), which is 56% off the RRP of US$79.99.
A great deal for a very useful piece of software if you use a Mac; this virtualisation software allows you to run Windows within Mac OS X. VirtualBox is another alternative, which is free, and there's also Parallels, but at this price the feature set of VMware Fusion is hard to beat.
It says they've exhausted their allotment of serial numbers but more will be coming soon.