CSS preprocessors have been around for awhile, but Andrey Sitnik's Autoprefixer takes the opposite approach: it parses your CSS after you write it and adds any necessary vendor prefixes using data from Can I Use.
As the browser landscape changes, your outputted CSS changes to fit. Without you having to do a thing. Andrey says:
The best tool is a tool you can't see and one that does the work for you
I have to agree with him on that.