Parallels Desktop (normally $80) is arguably the best way to virtualize Windows on your Mac side-by-side with OS X, and it's on sale today for a fraction of what it normally costs. Parallels currently costs $28, but you better make a move if you're interested because the price will rise by $4 every two hours until it reaches 25 percent off ($60)— where the price will stay through March 31st. After that date, Parallels will return to full price.