As part of their Lame Duck Challenge, CodeWeavers is offering fully supported copies of CrossOver and CrossOver Games today only. You can visit their web site and get your official serial number.
CodeWeavers is the corporate sponsor behind the Wine project, and CrossOver is the commercial version of that product. Their flagship product, CrossOver, is focused on the office market, with built-in installers for products like MS Office, PhotoShop, and others. CrossOver Games, as you might guess, is a similar product focused on gaming.
There are CrossOver products for both Linux and Mac.