An app that autocompiles .less files into CSS. I like this idea much more than having JS do the work on the front-end, or for that matter, having the server-side scripting language like PHP or Python compile it.
Paste your CSS into Prefixr and it will automatically add vendor prefixes for CSS3 properties. Even better, there’s an API available, so you can automate the change or hook into it from your favorite IDE.
We’ve gone too long without a good lint tool for CSS. This one provides syntax checking and applies “a set of rules to the code that look for problematic patterns or signs of inefficiency. The rules are all pluggable, so you can easily write your own or omit ones you don’t want.”